Immature Stages of Eucharitidae
Immature stages of Eucharitidae (= Eucharidae) were discussed in detail by Clausen (1940), as follows:
The eggs of the Eucharitidae are all of the stalked type and, because of the enormous numbers produced by each female, exceedingly minute. The egg body is ellipsoidal in form and greatly arched dorsally and ranges from 0.1 to 0.2 mm. in length in the different species. The slender anterior stalk is one‑fourth the length of the egg body in Psilogaster montanus as compared to twice its length in Psilogaster sp. and Stilbula cynipiformis. At deposition, the eggs are translucent, but as incubation progresses they assume a deep amber color, with the heads of the larvae appearing almost black.
The first‑instar larvae are all of the planidium type, distinguished by a large, heavily sclerotized head and heavy, segmental bands that terminate lateroventrally in pleural plates. Transparent membranes, which are not visible until feeding takes place, separate these bands and in active individuals the successive segments telescope into those preceding. Because of this, it is difficult to determine the exact number of body segments; but from on examination of cast skins, in which the bands are somewhat separated, the normal number appears to be 12, with the 13th segment represented by the unsclerotized caudal sucker.
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The greatest morphological differences between species are found in the form and in the spine equipment of the pleural plates. In Chalcura deprivata (Fig. 99), those of the first two segments are rounded, whereas on the following six segments they terminate in long, posteriorly directed spines which are free, except at the base. The posterior margins of the plates are notched, and those of the fourth and fifth abdominal segments bear a second pair of spines. The paired spines of the latter segment are twice the length of those preceding. The sixth to ninth abdominal segments have the segmental bands but no pleural plates, and the caudal cerci are borne dorsolaterally on the eighth segment. Sensory spines and setae are as shown in the figure.
In Schizaspidia manipurensis (Fig. 99), the sensory spines of the pleural plates are much longer than in Chalcura, and Kapala foveatella, described by Ishii, has the distal portion of the plates of the fifth abdominal segment greatly produced and projecting beyond the end of the body. Several species of other genera show a less pronounced modification of the plates of this segment.
The spiracles, if present, are exceedingly small and difficult to distinguish. In S. manipurensis, the single pair is situated at the anterior margin of the prothorax.
The second‑instar larva was known only in S. tenuicornis, K. terminalis and Stilbula cynipiformis by 1940 (Clausen 1940). That of Schizaspidia tenuicornis (Fig. lOOB) is shining white, with only nine distinguishable body segments, and the head is small, not heavily sclerotized, and situated ventrally. There are no sensory setae or integumentary spines. In K. terminalis, the body is bag‑like, with only faint indications of segmentation, and a single pair of spiracles is situated at the anterior margin of the mesothorax. Parker's (1932) examination of the 2nd exuviae of Stibula cynipiformis revealed a lack of segmentation, several transverse rows of minute setae, and two pairs of spiracles.
The mature larvae, which are the third instar, are robust in all species, and they differ principally in the distinctness of segmentation, the presence or absence of dorsolateral tubercles, and the integumentary ornamentation. The larva of Schizaspidia tenuicornis shows no segmentation except for constrictions between the three principal parts of the body. This is true of several other species, but in Eucharis sp. the segmentation is distinct. Large dorsolateral tubercles on the first 10 body segments have been noted only in Orasema. All species bear an anal lobe, usually hemispherical is form, which may represent the last segment.
Although sensory setae and integumentary spines are lacking, yet the body is completely or partly covered with minute papillae or tubercles.
There are usually nine pairs of spiracles, situated on the second and third thoracic and the first seven abdominal segments, though in several species there are said to be only eight. The two pairs on the thorax are much the largest.
It has been pointed out by Parker that the larva of Slilbula cynipiformis is devoid of tegumentary muscles, and this appears to be a normal condition in the family. In no species observed is the mature larva capable of ordered movement, and in many there is no visible physical reaction when they are disturbed.
The pupae of the Eucharidae present few distinguishing characters except in those species which have the scutellum produced into a bifurcate process, in which cases the pupal form is correspondingly modified (Fig. lOOD). The abdomen of the female is very large and bears intersegmental ridges over the dorsum and sides. Some species of Orasema, Schizaspidia, Kapala, and Chalcura bear welts on the lateral portions of these ridges. These welts, or pustules, are most pronounced in 0. coloradensis; the ridges of O. viridis are unmodified. The welts are globular in form and much constricted at the base and occur only on the posterior thoracic and petiolar regions, in 0. costaricensis.