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GUIDE TO INSECT FAMILIES, WITH EMPHASIS ON

PARASITOIDS & PREDATORS ^{1 2}

E. F. Legner, University of California, Riverside

(Email Contacts)

This key is in a form commonly used in North America. If the statement is true, proceed

to the designated couplet, whereas if it is false, go to the "b" portion of the couplet. Numbers

in parentheses refer to the previous couplet or couplets read. Details on families may be found

in <taxnames.htm>. See MORPHOLOGY to learn about insect structure. [For less powerful

connections, please try <insect1.htm> ]

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----Please CLICK on desired underlined categories to view pictures and to navigate in the key

[A will display all pictures for both pairs of a couplet]

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1a. Adults have well-developed wings................................................................................…................….......2

1b. Adults wingless or with wings vestigial or rudimentary (nymphs, larvae & some adults)….......….28

2a (1a). Wings membranous, not hardened or leathery..........................................................…….............….3

2b. Front wings hardened or leathery, at least at base (Figs.A-E); hind wings, if present, usually

membranous..... A….................................................................................................................................24

3a (3a). Only 1 pair of wings...............................................................................................................……..........4

3b. Two pairs of wings......................................................................................................................…....….....10

4a (3a). Body shaped like a grasshopper; pronotum ( = dorsal plate or sclerite of prothorax)

extends back over abdomen and is pointed apically; hind legs enlarged (Figs.A-F)

…………………………………………………......……. [pygmy grasshoppers... A......Orthoptera

4b. Body not shaped like a grasshopper; pronotum not as previous; hind legs not so enlarged

..................................................................................................................................…......................….....5

5a (4b). Antennae with at least 1 segment bearing along lateral process; front wings minute,

hind wings like a fan (Figs.A-B); minute insects [male twisted-winged parasitoids) A

………………………………………………………………........…........................Strepsiptera..…..217

5b. Does not fit previous description exactly.................................................................................…....…..... 6

6a (5b). Abdomen with 1-3 thread-like or bristle-like caudal (= tail) filaments; mouthparts vestigia........7

6b. Abdomen without thread-like or bristle-like caudal filaments; mouthparts almost always

developed, mandibulate (= chewing) or for sucking....………............................................….......…....8

7a (6a). Antennae long and conspicuous; abdomen terminates in one long style (rarely 2); wings

with a single forked vein (Fig.A); halteres (= knobbed modified hind wings) present

and usually terminating in a hooklike bristle; minute insects, usually <5 mm in length

[male scale insects] ........ A.......................................................................................…......Homoptera

7b. Antennae short, bristle-like, and inconspicuous; abdomen with 2-3 thread-like caudal

filaments; wings with numerous veins and cells; halteres absent; usually >5 mm in length

(Fig. A) [mayflies]...........................................................................................................Ephemeroptera

8a (6b). Tarsi almost always with 5 segments; mouthparts for sucking; hind wings knob-like, reduced to

halteres (Figs.A-E); body lightly sclerotized (= hardened) [flies]..... A..........Diptera...........88

8b. Tarsi with 2-3-segments; mouthparts variable; hind wings reduced or absent, not haltere-

like.........................................................................................................……..............................................9

9a (8b). Mouthparts mandibulate (Figs.A-E)[psocids]...... A...................................................Psocoptera

9b. Mouthparts for sucking (Figs.A-C) [some planthoppers & leafhoppers]............................Homoptera

10a (3b). Wings mostly or entirely covered with scales (Fig. A); mouthparts usually in the

form of a coiled proboscis (Fig.B); antennae with many segments (Figs.C-G)

[butterflies & moths] ... A................................................................................Lepidoptera….....227

10b. Wings not covered with scales; mouthparts not a coiled proboscis, antennae variable…….........11

11a (10b). Wings long and narrow, veinless or with only 1-2 veins, and fringed with long hairs

(Fig.A); tarsi with 1-2 segments, the last segment swollen; minute insects, usually <5 mm

in length (Figs.A-D) [thrips]....... A...........................................................................Thysanoptera

11b. Wings not as previously described , or if wings are somewhat linear, then the tarsi have more than 2

segments.…………...................................................................................................................…….......12

12a (11b). Front wings relatively large and usually triangular; hind wings small and usually

rounded, the wings at rest held together above the body; wings usually with many veins

and cells; antennae short, bristle-like, and inconspicuous; abdomen with 2-3 thread-like

caudal filaments (Fig.A); delicate, soft-bodied insects (Fig.B) [mayflies]... A..Ephemeroptera

12b. Not as previously described......................................................................................…..….......................13

13a (12b). Tarsi with 5 segments......................................................................................…..................….........14

13b. Tarsi with 4 or less segments....................................................................................................……..........17

14a (13a). Front wings obviously hairy; mouthparts usually very much reduced except for the

palps; antennae usually as long as body or longer; somewhat soft-bodied insects

(Figs.A-F) [caddis flies.... A...................................................................….......................Trichoptera

14b. Front wings not hairy, at the most with microscopic hairs; mandibles well developed;

antennae shorter than body....................................................................................................…...........15

15a (14b). Body quite hard, wasplike insects; clypeus not elongated; the abdomen often

constricted at base, 1st abdominal segment fused to thorax; fore wings distinctly larger

than hind wings and with fewer veins; front wings with 20 or less cells (Figs.A-F)

[sawflies, bees and wasps]....... A................................................................Hymenoptera……...118

15b. Body soft, not wasplike, the abdomen not constricted at base; hind wings about the same

size as front wings and usually with about as many veins; front wings frequently with more

than 20 cells.................................................................................................................................…..........16

16a (15b). Costal area of front wings (= area just behind anterior margin) nearly always with

numerous cross veins per pair of longitudinal veins (Fig.A), or if not (Fig.B) then hind wings shorter

than front wings; mouthparts not prolonged ventrally into a beak

(Figs.C-G) [lacewings, dobsonflies, antlions] ... A.......................................Neuroptera……..194

16b. Costal area of front wings with not more than 2-3 cross veins per pair of longitudinal veins (Fig.A);

mouthparts prolonged ventrally to form a beak-like process (Figs.B-D)

[scorpionflies]....................................................................................................................….....Mecoptera

17a (13b). Hind wings as long as front wings and of the same shape or wider at base, the wings

at rest held above the body or extended out (never held flat over abdomen); wings with

many veins and cells; antennae short, bristle-like, and inconspicuous; abdomen long and

slender (Figs.A-B); tarsi with 3 segments; length 20-85 mm [dragonflies, damselflies) A

...............................................................................................................…….......................……...Odonata

17b. Not as previously described.................................................................................................…….............18

18a (17b). Mouthparts for sucking.................................................................................……...........................19

18b. Mouthparts mandibulate (= chewing).....................................................................…...............…..........20

19a (18a). Beak arises from front part of head (Figs.A-E) [gnat bugs..Hemiptera /Heteroptera...A..140

19b. Beak arises from hind part of head (Fig.A) [cicadas, some hoppers, aphids, some

psyllids and whiteflies].........................................................................…..............................Homoptera

20a (18b). Tarsi with 4 segments; front and hind wings similar in size, shape and venation

(Figs.A-E) cerci tiny or absent [termites]..... A........…………............................................…..........Isoptera

20b. Tarsi with 3 or less segments; hind wings usually shorter than front wings; cerci either

present or absent.....................................................................................................................……............21

21a (20b). Hind wings with anal area nearly always enlarged and forming a lobe, which is folded

like a fan at rest; venation varying from normal to very dense, the front wings usually with

several cross veins between Cu-1 and M and between Cu-1 and Cu-2 (Fig. A); cerci

present and often fairly long; mostly 10 mm or more in length; nymphs aquatic, and adults

usually near water (Figs.A-F) [stoneflies].... A.............................................................Plecoptera

21b. Hind wings without an enlarged anal area and not folded at rest; venation normal or

reduced, with no extra cross veins; short cerci present or absent; mostly 10 mm in length

or less; nymphs not aquatic and adults not regularly near water.........................................….......22

22a (21b). Tarsi with 3 segments, basal segment of front tarsi enlarged A

……………………………………………................………… (Figs.A-B) [webspinners].Embioptera

22b. Tarsi with 2-3 segments, basal segment of front tarsi not enlarged................................……….........23

23a (22b). Cerci present; tarsi with 2 segments; wing venation reduced (Figs.A-D); moniliform

(= bead-like) antennae with 9 segments............. A...........................................................Zoraptera

23b. Cerci absent; tarsi with 2-3 segments; wing venation not much reduced (Figs.A-D); antennae not

moniliform, usually long and hairlike, with 13 or more segments

.....................................................................................................................…...........................Psocoptera

24a (2b). Mouthparts for sucking, beak elongated and usually segmented (Figs.A-B)... A ....…......25

24b. Mouthparts mandibulate........................................................................................…................….............26

25a (24a). Beak arises from front of head (Fig.A); basal portion of fore wing usually

thickened and leathery, but membranous at tip, the tips overlapping at rest (Fig.B) A

[true bugs]..........................................................................................Hemiptera / Heteroptera.…...140

25b. Beak arises from hind part of head, often appearing to begin at base of front legs; front

wings of uniform texture throughout, the tips not, or only slightly, overlapping at rest

[leafhoppers & some psyllids].....................................................................….......................Homoptera

26a (24b). Abdominal cerci like forceps (Fig.A); front wings short, leaving most of

abdomen exposed; tarsi with 3 segments (Fig.A) [earwigs]...... A........….................Dermaptera

26b. Abdominal cerci not like forceps, or if cerci appear as such, then front wings cover most of

abdomen; tarsi variable..........................................................................................................………...........27

27a (26b). Front wings entirely leathery and without veins and usually meet in a straight line

down middle of back; antennae generally with 11 or fewer segments and have diverse

shapes (Figs.A-I); hind wings narrow, usually longer than front wings when unfolded, and

with few veins (Figs.J-O) [beetles].... A............................................................Coleoptera.…....152

27b. Front wings with veins and either held like a roof over abdomen or overlapping over

abdomen when at rest; antennae generally with >12 segments; hind wings broad, usually

shorter than front wings, and with many veins (Fig.A), usually folded like a fan at rest

[crickets, grasshoppers, cockroaches and preying mantids].....................…...................Orthoptera

28a (1b). Body usually insect-like, with segmented legs and usually segmented antennae……............29

28b. Body generally worm-like, body regions (except possibly head) not well differentiated, and

segmented thoracic legs absent; antennae present or absent........................................…......……....74

29a (28a). Front wings present but rudimentary; hind wings absent or represented by halteres;

tarsi almost always with 5 segments [some flies]........................................................Diptera……......88

29b. Wings entirely absent or with 4 rudimentary wings and no halteres; tarsi variable.........……........30

30a (29b). Antennae absent; length 1.5 mm or less (Fig.A); usually occur in soil or leaf litter. A

..................................................................................................................................................Protura

30b. Antennae usually present (sometimes small); size and habitat variable............................…….........31

31a (30b). Ectoparasites of birds, mammals, or honey bees and usually found on the host; body

somewhat leathery and usually flattened dorsoventrally or laterally..........................................32

31b. Free-living (not ectoparasitic), terrestrial or aquatic................................................................……......36

32a (31a). Tarsi with 5 segments; antennae short and usually concealed in grooves on head;

mouthparts for sucking..................................................................................…...............…..............33

32b. Tarsi with fewer than 5 segments; antennae and mouthparts variable.........................……..............34

33a (32a). Body flattened laterally; usually jumping insects, with rather long legs (Fig.A) A

[fleas]...............................................................................................................................Siphonaptera

33b. Body flattened dorsoventrally; not jumping insects, legs usually short (Fig.A) [louse

flies, bat flies & bee lice]............................................................................................…............Diptera

34a (32b). Antennae decidedly longer than head; tarsi 3-segmented (Fig.A) [bed bugs and A

bat bugs]........................................................................................................Hemiptera / Heteroptera

34b. Antennae not longer than head; tarsi with 1 segment...........................................................………....35

35a (34b). Head as wide as or wider than prothorax; mouthparts mandibulate; parasites of birds

(with 2 tarsal claws) and mammals (with 1 small tarsal claw) (Figs.A-D) A

…………………………………………………………................………….[chewing lice] Mallophaga

35b. Head usually more narrow than prothorax; mouthparts haustellate (= for sucking);

parasites of mammals with 1 large tarsal claw (Figs.A-B) [sucking lice]…………..........…. Anoplura

36a (31b). Mouthparts for sucking, with a conical or elongated beak enclosing stylets...…….......…....37

36b. Mouthparts mandibulate (sometimes hidden in head), not beaklike.......................……....................41

37a (36a). Tarsi with 5 segments; maxillary or labial palps ( = segmented processes) present

.............................................................................................................................…..................................38

37b. Tarsi with 4 or fewer segments; palps small or absent........................................................……..........39

38a (37a). Body covered with scales; beak usually in the form of a coiled tube; antennae long

and with many segments [wingless moths]......................................................Lepidoptera…...227

38b. Body not covered with scales; beak not coiled; antennae variable, but often short, with 3 or

less segments [wingless flies]......................................................................................Diptera.………..88

39a (37b). Mouthparts in the form of a cone located basally on ventral side of head; palps

present but short; body elongated, usually <5 mm in length; antennae about as long as

head and prothorax combined, not bristle-like, and 4-9 segmented; tarsi 1-2 segments,

often without claws (Fig.A) [thrips....... A.......................................…............….......Thysanoptera

39b. Mouthparts as an elongated segmented beak; palps absent; other characters variable.……........40

40a (39b). Beak arises from front part of head; antennae with 4-5 segments and not bristle-like;

tarsi usually with 3 segments; abdomen without cornicles (= dorsal tubular structures on

posterior abdomen ) [true bugs]. ... A......................................Hemiptera / Heteroptera.....….140

40b. Beak arises from rear of head; antennae either with >5 segments (and tarsi with 2

segments) or bristle-like (and tarsi with 3 segments); abdomen often with a pair of

cornicles (Fig.A) [aphids, hoppers, etc.]...............................................................................Homoptera

41a (36b). Abdomen very constricted at base; antennae often elbowed; tarsi with 5 segments;

bodies hard, ant-like [ants & wingless wasps]................................................Hymenoptera.....118

41b. Abdomen not very constricted at base; antennae not elbowed; tarsi variable..............……..........42

42a (41b). Abdomen with 3 long thread-like caudal filaments and with style-like appendages on

some abdominal segments (Fig.A); mouthparts mandibulate, but often somewhat A

retracted into head; body almost always covered with scales; terrestrial [bristletails].….....…..43

42b. Abdomen with only 2 thread-like caudal filaments or none; if with 3 [mayfly nymphs]

then aquatic; other characters variable................................................................................……….......44

43a (42a). Compound eyes large and usually contiguous; body somewhat cylindrical, with

thorax arched; ocelli present; middle and hind coxae often with styli; abdominal styli (=

bristlelike processes) on segments 2-9 (Fig.A).... A..........................……..............Microcoryphia

43b. Compound eyes small and widely separated or absent; body somewhat flattened

dorsoventrally, thorax not arched; ocelli present or absent; middle and hind coxae without styli;

abdominal segments 1-6 (sometimes 7) without styli (Fig.A) [silverfish] ……......…..Thysanura

44a (42b). Aquatic insects, often with tracheal gills (= protruding externally at spiracles ).….......…...45

44b. Terrestrial insects, without tracheal gills.................................................................……...........….........52

45a (44a). Nymphs; compound eyes and usually wing pads present..............................……...................46

45b. Larvae; compound eyes and wing pads absent..........................................................……...................48

46a (45a). Prehensile labium (= lower lip), folded under head at rest, and when extended much

longer than head (Figs.A-G) [dragonfly and damselfly nymphs]...... A...…................Odonata

46b. Labium normal, not as previously described...............................................................……...................47

47a (46b). Having 3 caudal filaments; tarsi with 1 claw; gills located on lateral margins of

abdominal terga (= dorsal plates or sclerites) and usually leaflike or plate-like A

(Figs.A-C) [mayfly nymphs]........................................................................................Ephemeroptera

47b. With 2 caudal filaments; tarsi with 2 claws; gills mostly present, somewhat fingerlike,

usually located on underside of thorax (Figs.A-D) [stonefly nymphs]..............................Plecoptera

48a (45b). Having 5 pairs of prolegs (= fleshy abdominal legs) on ventral side of abdomen, the

prolegs with tiny hooks (crochets) [aquatic caterpillars].................................Lepidoptera.....227

48b. Abdominal segments without prolegs or with only one terminal pair..........................…........….....49

49a (48b). Mouthparts with 2 slender and elongated structures, longer than head; antennae long

and slender, or least 1/3rd as long as body; tarsi with 1 claw (Fig.A); live in freshwater

sponges [Sisyridae larvae]..... A.........................................................Neuroptera.….................194

49b. Mouthparts, and usually also antennae, short and not as described previously.........…...….......50

50a (49b). Tarsi with 2 claws; abdomen with long slender lateral processes and a long slender

terminal process (Figs A & B) [Sialidae] or with slender lateral processes and a pair of hooklike structures

apically (Fig. C.) [Corydalidae, fishfly and alderfly larvae]...... A...........................Neuroptera.....194

50b. Tarsi with 1-2 claws; if with 2, then abdomen not as described previously........................51

51a (50b). Abdomen with a pair of hooks, usually on anal prolegs, at posterior end and without

long lateral processes (but at times with finger-like gills); tarsi with 1 claw; usually living

in cases (Figs.A-F) [caddisfly larvae]..... A............................................…............…....Trichoptera

51b. Abdomen with 4 hooks at posterior end or none, and with or without long lateral

processes; tarsi with 1-2 claws (Fig.A); not living in cases [beetle larvae].......................

........................................................................................................…........................... Coleoptera......152

52a (44b). Mouthparts usually withdrawn into head and not obvious; abdomen with stylelike

appendages on some segments or with a forked appendage near end of abdomen; usually

<7 mm long....................................................................................................…................….....................53

52b. Mouthparts usually distinct, mandibulate or haustellate (= for sucking); abdomen without

appendages as described previously; size variable...................................................…….........…........54

53a (52a). Antennae long, with many segments; abdomen with at least 9 segments and with

stylelike appendages on ventral side of some segments; without a forked appendage near

end of abdomen, but with well developed cerci (Figs.A-C) ... A...............…….................Diplura

53b. Antennae short, with 6 or less segments; abdomen with 6 or less segments and usually with

a forked appendage near posterior end (Figs.A-G) [springtails] ………………….........…Collembola

54a (52b). Body larviform ( = shaped like a worm or larva), thorax and abdomen not

differentiated; compound eyes present [larviform beetles]……......……… Coleoptera…......152

54b. Body shape variable, but if larviform, then without compound eyes.................................…….........55

55a (54b). Compound eyes usually present; body shape variable, but usually not worm-like;

wing pads often present [adults & nymphs]...................................................................................56

55b. Compound eyes and wing pads absent, body usually worm-like in shape [larvae].....…..…..........65

56a (55a). Tarsi with 5 segments...................................................................................…….............................57

56b. Tarsi with 4 or less segments..................................................................................….….........................59

57a (56a). Mouthparts prolonged ventrally into a snout-like process (Fig.A); body somewhat A

cylindrical and usually <15 mm long (Fig.A) [wingless scorpionflies].......…................. Mecoptera

57b. Mouthparts not as previously described; body shape and size variable..............….........................58

58a (57b). Antennae with 5 segments; Texas (some && twisted-winged parasitoids;..

Mengeidae].........................................................................................Strepsiptera.….....................217

58b. Antennae with >5 segments; widely distributed (Figs.A-G) [rock crawlers, walking A

sticks & some cockroaches]......................................................................…........................Orthoptera

59a (56b). Cerci like forceps; tarsi with 3 segments.................................................……...............................60

59b. Cerci absent or, if present, not like forceps; tarsi variable...................................…….........................61

60a (59a). Antennae more than 1/2 as long as body; cerci short; western U.S.A. [Timemidae]

…………................................................................................................…..........................Orthoptera

60b. Antennae usually less than 1/2 as long as body; cerci long (Fig.A); widely distributed A

[earwigs]………………………………………………………………………...............…..… Dermaptera

61a (59b). Tarsi with 3 segments, basal segment of front tarsi enlarged (Figs.A-B)

[webspinners]...........................................................................................…..........................Embioptera

61b. Tarsi with 2-4 segments, basal segment of front tarsi not enlarged.....................…........…...............62

62a (61b). Appearance like grasshoppers, with hind legs enlarged and fitted for jumping; length

usually >15 mm (Figs.A-E) [grasshoppers]… A……...…………………............… Orthoptera

62b. Not like grasshoppers, hind legs usually not as previously described; length <10 mm ….....…....63

63a (62b). Tarsi with 4 segments; pale, soft bodies, wood- or ground-inhabiting insects A

(Figs.A-E) [termites]................................................................................................................Isoptera

63b. Tarsi with 2-3 segments; color and habits variable..................................................…............…..........64

64a (63b). Cerci present, 1 segmented, and terminating in a long bristle; antennae with 9

segments and moniliform (Figs.A-C); compound eyes and ocelli absent (= simple

eyes); tarsi with 2 segments.... A...............................................................................…......Zoraptera

64b. Cerci absent; antennae with 13 or more segments and usually hair-like (Fig.A);

compound eyes and 3 ocelli usually present; tarsi with 2-3 segments [psocids]...............

.........................................................................................................................................…......Psocoptera

65a (55b). Ventral prolegs (= fleshy abdominal legs) present on 2 or more abdominal segments

(Figs.A-B)..... A.....................................................................................…….................................66

65b. Abdominal prolegs absent or on terminal segment only.........................................…….....................68

66a (65a). Have 5 pairs prolegs (on abdominal segments 3-6 & 10) or fewer (Fig. A), the prolegs with

tiny hooks (crochets); several (usually 6) ocelli on each side of head [caterpillars]

.............................................................................................................................. Lepidoptera…….....227

66b. Have 6 or more pairs of abdominal prolegs, the prolegs without crochets; ocelli number

variable ..........................................................................................................................................…….......67

67a (66b). Ocelli, 7 or more, on each side of head; prolegs on segments 1-8 or 3-8, usually faint

pointed structures (Fig.A) [scorpionfly larvae]........ A...............................................Mecoptera

67b. Ocellus (one) on each side of head; prolegs fleshy and not pointed, usually on abdominal

segments 2-8 & 10, sometimes on 2-7 or 2-6 & 10 (Figs.A-B) [sawfly larvae]

................................................................................................................................Hymenoptera.……..118

68a (65b). Mandible and maxilla on each side united to form a sucking jaw that is often long

(Figs.A-B); tarsi with 2 claws; labrum absent or fused with head capsule; maxillary A

palps absent [Planipennia: lacewing & antlion larvae]................................Neuroptera…..........194

68b. Mandibles and maxillae not as previously described; tarsi with 1-2 claws; labrum and

maxillary palps usually present....................................................................................................…….....69

69a (68b). Head and mouthparts prognathous (= directed forward), the head ca. as long along

midventral line as along middorsal line and usually cylindrical or a bit flattened ....…............70

69b. Head and mouthparts hypognathous (= directed ventrally), the head much longer along

middorsal line than along midventral line and usually rounded...........................………...................72

70a (69a). Tarsi with 1 claw [some beetle larvae]..............................................................……......Coleoptera

70b. Tarsi with 2 claws...................................................................................................................……............71

71a (70b). Distinct labrum (= upper lip) and clypeus (= hardened plate on lower face between

frons and labium) present [Raphidiodea: snakefly larvae]...............................Neuroptera.....194

71b. Labrum absent or fused with head capsule [most Adephaga: beetle larvae]..…….....…..Coleoptera

72a (69b). Front legs noticeably smaller than other pairs; middle and hind legs projecting

laterally much more than front legs; a small group of ocelli (usually 3) on each side of head behind

bases of antennae; tarsal claws absent; length <5 mm; usually found in moss

[Boreidae larvae]...........................................................................................…...............….....Mecoptera

72b. Legs not as previously described, front and middle legs ca. same size and position; ocelli

variable; tarsi with 1-3 claws; size and habitat variable.......................................…...........……...........73

73a (72b). Tarsi with 1-2 claws; abdomen usually without caudal filaments; antennae variable

[beetle larvae]............................................................................................................…........Coleoptera

73b. Tarsi usually with 3 claws; abdomen with 2 caudal filaments ca. 1/3rd as long as body (Fig.A);

antennae usually short with 3 segments [triungulin (= active 1st instar) larvae A

of some beetles, Meloidae, and twisted-winged parasitoids]..........................................

.........................................................................Coleoptera.....152 and ................ Strepsiptera…....217

74a (28b). Aquatic [fly larvae]......................................................................................................……......Diptera

74b. Terrestrial or parasitic (not aquatic).....................................................................................…….............75

75a (74b). Sessile, plant feeding; body covered by a scale or waxy substance; mouthparts for

sucking, long and thread-like [female scales]............................................................…...Homoptera

75b. Not the same as previously described..................................................................................……...........76

76a (75b). Head and thorax almost fused, and abdominal segmentation indistinct (Fig.A); A

internal parasitoids of other insects [female twisted-winged parasitoids]...Strepsiptera.....222

76b. Head not fused with thorax, body segmentation distinct; habitat variable...........……....................77

77a (76b). Head distinct, sclerotized, and usually pigmented and exserted...................……....................78

77b. Head indistinct, incompletely or not at all sclerotized, sometimes retracted into thorax…......…...85

78a (77a). Head and mouthparts prognathous (= directed forward), the head ca. as long along

midventral line as along middorsal line and usually cylindrical or slightly flattened..….........79

78b. Head and mouthparts hypognathous (= directed ventrally), the head much longer along

middorsal line than along midventral line and usually rounded.................................….......……......82

79a (78a). Terminal abdominal segment with a pair of short pointed processes; several long

setae on each body segment (Fig.A) [flea larvae]... A.................................…....Siphonaptera

79b. Not exactly as previously described.....................................................................…............…..............80

80a (79b). Labium with a protruding spinneret (= silk-producing structure); antennae arising

from membranous area at bases of mandibles; mandibles well developed, opposable; body

usually slightly flattened; ventral prolegs usually with crochets; mostly leaf miners in

leaves, bark, or fruits [moth larvae]....................................................................Lepidoptera......227

80b. Labium without a spinneret; antennae, if present, arising from head capsule; prolegs

without crochets......................................................................................................................…………...81

81a (80b). Mouthparts distinctly mandibulate, with opposable mandibles; spiracles usually

present on thorax and 8 abdominal segments; body shape variable [beetle larvae].....Coleoptera

81b. Mouthparts as previously described or with mouth hooks somewhat parallel and moving

vertically; spiracles variable, but usually not as previously described; body elongated

[Nematocera & some Brachycera fly larvae]....................................................…….................Diptera

82a (78b). Abdominal segments usually with 1 or more longitudinal folds laterally or

lateroventrally; body C-shaped, scarabaeiform (Fig.A); 1 pair of spiracles on thorax

and usually 8 pairs on abdomen [beetle larvae, white grubs].... A...........……..........Coleoptera

82b. Abdominal segments without longitudinal folds, or if present, then spiracles not as

previously described............................................................................................……...............................83

83a (82b). Head with adfrontal areas (= pair of narrow oblique sclerites on head) (as in

Fig.A); labium with a projecting spinneret; if present, antennae arise from

membranous area at base of mandibles; often 1 or more ocelli (usually 6) on each side of

head; ventral prolegs, if present, with crochets [moth larvae]..……..............................Lepidoptera

83b. Head without adfrontal areas, and labium without a spinneret; antennae and ocelli not as

previously described; prolegs, if present, without crochets......................................….........…..........84

84a (83b). Mandibles not heavily sclerotized and not brush-like; spiracles usually present on

thorax and most abdominal segments, the posterior pair not enlarged; larvae occur in plant tissues

as phytophagous parasites, or in cells constructed by adults [Apocrita]….Hymenoptera.....118

84b. Mandibles usually brush-like; spiracles usually not as previously described-- if present on

several abdominal segments, the posterior pair is much larger than the rest; occur in wet

places, in plant tissues, or as internal parasites (Fig.A) A [fly larvae, mainly Nematocera]

............................................................................................................................…...........................Diptera

85a (77b). Mouthparts mandibulate, with opposable mandibles and maxillae; antennae

usually present [beetle larvae].......................................................................................…....Coleoptera

85b. Mouthparts reduced or modified, with only the mandibles opposable, or with parallel

mouth hooks present; antennae usually absent..................................................................……...........86

86a (85b). Body behind "head" (first body segment) consisting of 13 segments; full grown

larvae usually with a sclerotized ventral plate ("breast bone") located ventrally behind head

[Cecidomyiidae larvae]..............................................................................................................Diptera

86b. Body with fewer segments than previously described; no "breast bone".........................……........87

87a (86b). Mouthparts consist of 1-2 (if 2 then parallel, not opposable) median, dark colored,

down curved mouth hooks [Cyclorrhapha maggots]............................................................Diptera

87b. Mandibles opposable, but at times reduced, without mouth hooks as described previously

[Apocrita larvae].......................................................................................................................Hymenoptera

Major Families of Adult Entomophagous Diptera: (for muscoid flies see Figs C-D wing venation)

88a (8a, 29a & 38b). Antennae moniliform, 6-39 segments, longer than thorax.......……............…..........89

88b. Antennae with 3-4 segments, ring-like segments may be present; antennae shorter than

thorax.. .........................................................................................................................................................94

89a (88a). Costa (= longitudinal wing vein) extends completely around wing, occasionally

weakened behind.................................................................................................................................90

89b. Costa does not reach to or extend only slightly beyond wing tip ..........................................……....92

90a (89a). Mesonotal suture (= dorsal sclerite of mesothorax) transverse, not V-shaped..…..........…....91

90b. Mesonotum with an entire V-shaped suture; females with long sclerotized ovipositor

(Figs.A-B) (larvae are predators of aquatic or semiaquatic arthropods) A

..............................................................................................……...............................(Diptera) Tipulidae

91a (90a). Ocelli present and/or venation reduced; eyes meet above antennae; wing not scaly

(Figs.A-C) A (larvae are predators of Homoptera & mites).…........(Diptera) Cecidomyiidae

91b. Ocelli absent; probosis extends far beyond clypeus; wing venation strong; wing veins and

margin covered with scales, usually also on body (Figs.A-G) (larvae of some species

are predators of aquatic arthropods)..................................................……..........(Diptera) Culicidae

92a (89b). Ocelli absent......................................................................................……..........................................93

92b. Ocelli present; tibiae with apical spurs; discal cell in wing (= enlarged cell in basal or

central part of wing) absent (Figs.A-C) A (larvae spin webs & feed on entrapped

arthropods)......................................................................…...................……..(Diptera) Mycetophilidae

93a (92a). Head rounded behind, mouthparts piercing; metanotum short and rounded, without a

longitudinal groove (Fig.A) A (adults are blood-suckers; larvae are predators) ..............

...................................................................................……….........................(Diptera) Ceratopogonidae

93b. Head flat behind, mouthparts without mandibles, not piercing ;metanotum long, with a

median longitudinal groove (Figs.A-B) (most are predators, one species parasitizes

mayflies)...................................................................………...............................(Diptera) Chironomidae

94a (88b). Empodium (= pad or bristlelike structure at apex of last tarsal segment between the

claws) developed lobelike, the 3 pads almost equal.....................................…..............................95

94b. Empodium hair-like or absent................................................................................…..................…...........99

95a (94a). Third antennal segment compound, composed of ring-like segments...........……..…..............96

95b. Third antennal segment simple, frequently bearing an elongated style or arista...………................97

96a (95a). Tegula (= scale-like structure overlying front wing base) large and conspicuous

female abdomen large (Figs.A-F) A (adults are blood-suckers; larvae are predators of

aquatic arthropods) .................................................................…….......................(Diptera) Tabanidae

96b. Tegula small or vestigial; tibial spurs usually absent (Figs.A-F) (larvae are predators

of arthropods in several habitats).........................................……...............(Diptera) Stratiomyiidae

97a. Tegula small or vestigal............................................…………………….....……......................................98

97b. Tegula large, covering haltere; head very small, positioned low down and composed

almost entirely of compound eyes; body humpbacked (Fig.A) A (parasitoids of spiders)

………………………………………………………………….................……..(Diptera) Acroceridae

98a (97a). Tibiae without apical spurs; wing venation intricate with many veins ending before

wing tip (Figs.A-B) (parasitoids of grasshoppers).... A....…........(Diptera) Nemestrinidae

98b. At least middle tibia with apical spurs; antennae have long terminal style; wing venation

normal, not complex (Figs.A-B) (both adults and larvae are predators of other

arthropods)...........................................................................................................(Diptera) Rhagionidae

99a (94b). Wing with 2 or more submarginal cells (vein R-4+5 forked); 3-4 posterior cells……......….100

99b. Wing with only one submarginal cell or none at all (vein R-4+5 not forked)....………..................106

100a (99a). Front strongly concave at vertex........................................................…..…………...................101

100b. Front not concave between eyes, vertex flat or convex....................................……........................102

101a (100a). Three ocelli present; palpi normally prominent; proboscis adapted for piercing (Figs.A-E);

top of head hollowed out between eyes; abdomen tapering or oval; lobe A

(alula) usually at base of wing (both larvae & adults are predators) …....(Diptera) .. Asilidae

101b. One ocellus or none present; antennae with 4 segments; palpi vestigial; proboscis with

fleshy labellae (= exposed tip of labium); large flies (Figs.A-C) (both larvae & adults

are predators)..............................................................................…................…......(Diptera) Mydaidae

102a (100b). Costa continues around wing.............................................................................……...............103

102b. Costa reaches only to wing apex; 4th vein (M-1) ends before wing tip; 3 posterior cells

(Figs.A-B) (larvae are predators of larvae of Coleoptera).. A...................(Diptera) Scenopinidae

103a (102a). Wing has 5 posterior cells.......................................................................................……...........104

103b. Wing has at most 4 posterior cells..........................................................................…............….........105

104a (103a). Fourth vein (M-1) ends beyond apex of wing (Figs.A-C) (larvae & adults are A

predators of other arthropods) .........................................…......................(Diptera) Therevidae

104b. Fourth vein (M-1) ends before apex of wing (Fig.A) (both adults & larvae are

predatorsof other arthropods; rare in arid regions of western North America) ...................

............................................................................................……...........................(Diptera) Apioceridae

105a (103b). Anal cell open or closed near wing margin; antennal style short, never longer than

3rd antennal segment; body usually hairy, stocky and somewhat humpbacked; brown or

grayish flies (Figs.A-C) (parasitize a variety of immature arthropods; most common

in southwestern United States)....... A..............................……..................(Diptera) Bombyliidae

105b. Anal cell short and closed far from wing margin; anal vein does not reach wing margin;

antennal style (= bristle) usually longer than 3rd antennal segment; body usually bare,

slender and black (Fig.A) (predators of small arthropods).......……...............(Diptera) Empididae

106a (99b). Wing normal, not obviously rounded apically; venation normal.....……..............................107

106b. Wing rounded apically; veins very well developed anteriorly; antennae appear 1-

segmented with long arista (= bristle on apical segment); long hind legs and flattened

femora; body humpbacked (Fig.A) (parasitoids of ant pupae, larvae & pupae of

Lepidoptera & Hymenoptera; some species are predators ... A.......……....(Diptera) Phoridae

107a (106a). Spurious vein (= vein-like thickening of wing membrane between 2 true veins) in

wing absent; anal cell usually short....................................................………..........................108

107b. Spurious vein in wing present; anal cell long, closed near wing margin; body brightly

colored; they resemble bees or wasps) (Figs.A-E) (predators of Homoptera) A

......................................................................................................….......................(Diptera) Syrphidae

108a (107a). Frontal lanule (= crescent-shaped sclerite above base of antennae) completely

absent...........................................................................................…………...................................109

108b. Frontal lunule present as a crescent-shaped sclerite above antennae...............……....................111

109a (108a). Head normal, not exceptionally large; front and face usually wide........…….....................110

109b. Head large, hemispherical; front and face narrow; probosis small and soft; body stocky

and humpbacked, brown or grayish (Figs.A-B) (parasitoids of treehoppers & leafhoppers)

……………………………………………………………………........A..….(Diptera) Pipunculidae

110a (109a). Crossvein r-m located beyond basal 1/4th of wing; anal cell pointed apically;

proboscis usually rigid; body not metallic; %% genitalia terminal, not folded under

abdomen (Fig.A); relatively slender and usually black flies (adults and larvae are A

predaceous on smaller insects) (please also refer to couplet 105)..…...........(Diptera) Empididae

110b. Crossvein r-m located in basal 1/4th of wing; 2nd basal and discal cells united; anal cell

when present rounded apically; body usually metallic; %% genitalia frequently folded

forward under abdomen (Fig.A) (predators of small arthropods) .......................

...........................................................................................…….................... (Diptera) Dolichopodidae

111a (108b). Second antennal segment with a lateral subdorsal longitudinal seam; thorax with a

complete transverse suture; calypter (= lobe at wing base) large.......................……..........112

111b. Second antennal segment without a longitudinal seam; thorax without a complete

transverse suture; calypter small or rudimentary.....................................................……....................115

112a (111a). Hypopleural bristles (rather vertical row usually above hind coxae) present …................113

112b. Hypopleural bristles absent; 3rd (R-5) and 4th (M-1) veins almost parallel at wing tip or

4th vein bends forward; undersurface of scutellum with fine erect hairs (Figs.A-B) A

(predators of dipterous larvae)...........................................................................(Diptera) Anthomyiidae

113a (112a). Postscutellum developed; hypopleura with strong bristles; eyes usually bare; body

of && large, variously colored, but usually blackish (Figs.A-G) (parasitoids of many

types of insects).......... A...........................................................................(Diptera) Tachinidae

113b. Postscutellum not developed; hypopleura with a row of bristles............................…....................114

114a (113b). Body usually gray with 3 black stripes on mesonotum, bare but not metallic;

usually 4 notopleural bristles; arista usually plumose (= featherlike) in basal half A

(Figs.A-B) (parasitoids of grasshoppers & other arthropods) ........(Diptera) Sarcophagidae

114b. Body usually metallic, usually 2 (rarely 3) notopleural bristles; arista usually plumose beyond

basal half (Figs.A-D) (generally predaceous)...………………......................(Diptera) Calliphoridae

115a (111b). Proboscis shorter than head; head never broader than thorax; first posterior cell

not quite narrowed apically...................................................................................………............116

115b. Proboscis longer than head, slender and rigit, often folding; head wider than thorax; first

posterior cell narrowed or closed apically; abdomen clavate (= club-like), bent downward

at apex (Figs.A-B) (parasitoids of wild bees)..... A.........................................(Diptera) Conopidae

116a (115a). Costa broken at humeral crossvein; wings without pattern; postcellar bristles

divergent, if absent, arista is also absent (Fig.A)...... A....................(Diptera) Agromyzidae

116b. Eyes oval horizontally, 2X as long as high; costa not broken; postocellar bristles converge or are

absent, if absent, arista present; body grayish with yellowish markings on lateral thorax and

abdomen and on front (Fig.A) (predators of mites & Homoptera)......

.......................................................................................……............................(Diptera) Chamaemyidae

[Skip couplet 117a/117b]

118a (15a, 41a, 67b & 84a). Last sternite (= ventral plate) of female abdomen divided

longitudinally; ovipositor issues from anterior to tip of abdomen and has a pair of exserted

sheathes capable of covering ovipositor tip; hind wing usually without lobes......…................119

118b. Last sternite of && abdomen not divided longitudinally; ovipositor (or sting) issues from

the tip of abdomen and without a pair of exserted sheathes; hind wing often with an anal

lobe...................................................................................................………….........................................126

119a (118a). Wing venation well developed; stigma (= thickening of wing membrane along

costal border) well developed; hind trochanter with 2 segments...................

Hymenoptera).................................................. (Ichneumonoidea & Evanioidea)……............…....120

119b. Wing venation reduced; stigma absent or poorly developed; trochanter with 1 segment….......122

120a (119a). Costal cell absent; antennae with 16 or more segments (Figs.A-B)...... Wing Types...

......................................................... A.....(Hymenoptera) (Ichneumonoidea)..…....................…..121

120b. Costal cell present; antennae with fewer than 16 segments; abdomen short with long

petiole arising on propodeum (= posterior part of thorax that is actually 1st abdominal

segment), far above bases of hind coxae (Figs.A-B) (parasitoids of cockroach egg

capsules) .................................................................................(Hymenoptera) (Evanioidea) Evaniidae

121a (120a). Wing with one or no recurrent veins; propodeum not prolonged beyond hind

coxae .................................................................................................................................………....122

121b. Wing with 2 recurrent veins (= transverse veins posterior to cubital vein) or the

abdomen is 3X the body length (Figs.A-C) (parasitoids of numerous insect orders ) A

................................................................................(Hymenoptera) (Ichneumonoidea) Ichneumonidae

122a (121a). Abdominal terga 2 & 3 not fused (Fig.A) (parasitoids of aphids) ..........(Hymenoptera)

…………………………………A..............…….. (Ichneumonoidea) Braconidae (Aphidiinae)

122b. Abdominal terga 2 & 3 fused or the cubitus (= longitudinal vein just posterior to medial)

in fore wing arises from the radial cell (Figs.A-F) (parasitoids of many kinds of hosts,

excluding aphids) .......................................................(Hymenoptera) (Ichneumonoidea) Braconidae

123a (119b). Pronotum extends to tegula; antennae not geniculate (= elbow-shaped) ; body

often compressed................................................................... (Hymenoptera) (Cynipoidea).....124

123b. Pronotum does not reach tegula; prepectus (= area along anterior ventral margin of

mesepisternum outlined by a suture) present; antennae geniculate, with one or more

proximal segments of flagellum often reduced to ring-like segments; abdominal segment

behind propodeum always in form of a petiole, although not always clear.........................

...................................................................................(Hymenoptera) (Chalcidoidea)……................ 248

124a (123a). Largest segment of abdomen (side view) tergites 2 or 3 and never more than one

short tergite in front of the largest tergite...................................................................................125

124b. Largest segment of abdomen (side view) tergites 4, 5 or 6, with at least 2, 3 or 4 short

tergites behind petiole and preceding the largest tergite; abdomen very compressed laterally;

ovipositor curved under "membranous flap" (Fig.A) (parasitoids of sawflies A

in family Siricidae).........................……....................................(Hymenoptera) (Cynipoidea) Ibaliidae

125a (124a). Tergite 2 longest and usually forming at least 1/2 the abdomen; radial cell open

(except in Charips) and petiole without enlarged ring bearing longitudinal striations (gall-

formers and hyperparasitoids in aphids). If radial cell is closed and petiole has striated

ring, then tergites 2 & 3 are fused into a single saddle-shaped tergite that covers entire

abdomen (Figs.A-C) (Synergus inquilines in oak galls).............. A

. .......................................................…...........optera) (Cynipoidea) Cynipidae [also see fly-par.htm ]

125b. Tergite 2 clearly forming less than 1/2 of abdomen; radial cell closed; petiole with slightly

enlarged ring structure bearing longitudinal striations; mesopleura without spines or

scratches (Figs.A-B) (parasitoids of Diptera) ...............(Hymenoptera)….… (Cynipoidea) Figitidae

[also see fly-par.htm ]

126a (118b). Pronotum almost reaches or does reach tegula, but lacks a rounded lobe on lateral

margin......................................................................................................................…………….....127

126b. Pronotum short, does not reach tegula, with lateral rounded lobe; body hairs not branched

(Figs.A-L)........... A...........................................................(Hymenoptera) (Sphecoidea) Sphecidae

127a (126a). Venation of fore wing well developed; hind wing with veins or a basal lobe.……............128

127b. Venation of fore wing reduced; hind wing not lobed...(Hymenoptera) (Proctotrupoidea)..........137

128a (127a). Venation of hind wing reduced, lacking closed cells

...................................................................................(Hymenoptera) (Bethyloidea)………..............129

128b. Venation of hind wing not reduced, with at least one closed cell...................................…….........131

129a (128a). Antennae with 12-13 segments; tarsi normal..............................................…............….........130

129b. Antennae with 10 segments; fore tarsi of females often pincer-like (Figs.A-C) ..........

(parasitoids of leafhoppers) ........ A.................….........(Hymenoptera) (Bethyloidea) Dryinidae

130a (129a). Abdomen with 3 or less visible tergites (4 in male Parnopes); abdominal sternites

concave; body metallic green or blue (Figs.A-F) (parasitoids of wasps) ..............

..................................................... A...............................(Hymenoptera) (Bethyloidea) Chrysididae

130b. Abdomen with 6 (females) or 7 (males) tergites; sternites convex; body not metallic

(Figs.A-C) (parasitoids of Coleoptera & Lepidoptera)................................................

...............................................................................................(Hymenoptera