Immature Stages of Perilampidae
Immature stages of Perilampidae were discussed in detail by Clausen (1940), as follows:
The egg of P. chrysopae (Fig. 93) is subcylindrical and distinctly arched on one side with one end rather sharply pointed and the other bearing a short, broad peduncle. It is pearly‑white in color, and the chorion is characteristically sculptured, with irregular elongated areas that extend lengthwise. The eggs of P. tristis (Fig. 93) and P. italicus are very similar. The size of these eggs, which measure 0.25 mm. in length in P. chrysopae and 0.41 mm. in P. italicus, contrasts strongly with the very minute stalked eggs of the related Eucharidae.
The first‑instar larvae of Perilampus are all of the planidium type, with heavy segmental bands that almost reach the median ventral line. There are 13 body segments, of which the first 12 bear the sclerotized bands and the 13th is represented by the caudal sucker. Specific differences occur in the form of the terminal portions of the bands and in the number, size, and position of the body spines and the "scales" and hooks on the membrane of the venter of the anterior portion of the body. The pleural plates, which have been distinguished upon the planidia of the Eucharidae and of families of other orders having larvae of this type, are absent or not recognizable.
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On the larvae of P. hyalinus (Fig. 94A) and several others, the posterior margins of the terminal portions of each band bear numerous sharp teeth, whereas in P. chrysopae (Fig. 94B) they are smooth. The sensory spines are exceptionally long and heavy in the latter species. The two caudal cerci arise dorsolaterally from the last segmental band. In Perilampus sp. from Conocephalus (Ford 1922), they are about 1/2 the length of the body.
Spiracles have been detected in P. hyalinus, P. chrysopae, P. tristis, and several undetermined species; all these except the first have a single pair dorsolaterally at the anterior margin of the band of the second thoracic segment or on the membrane between the first and second segments. In P. hyaiinus, the spiracles are on the intersegmental membrane but distinctly ventral.
The number of larval instars is uncertain. Smith recognized only three in P .hyalinus, while Parker described four for the same species and Bergold & Ripper found the same number in P. tristis.
The second‑instar larva of P. hyalinus (Fig. 95B) lacks the specialized characters of the first instar, and the body is white and distinctly segmented. The sensory setae are small and set upon tubercles, and each segment bears a band of minute integumentary setae at the anterior margin. The two pairs of large spiracles are situated on the mesothorax and the first abdominal segment. The larva of P. chrysopae (Fig. 95A) is similar, though more robust, but in P. tristis the spiracles are said to be on the pro- and metathorax.
The third‑instar larva of P. hyalinus (Fig. 95C) is rather indistinctly segmented but still bears the sensory and integumentary setae mentioned for the second instar. There are now seven pairs of spiracles, situated on the last two thoracic and the first five abdominal segments, of which the first and third are largest. In P. tristis, the number and position are the same.
The fourth‑instar larva of P. hyalinus (Fig. 95D), which is the mature form, is distinctive, being very robust and bent ventrally in the thoracic region, with large lateral segmental "bosses" on the first 5 abdominal segments and distinct fleshy tubercles of testaceous color at the lateral margins of the second and third thoracic segments. The sensory and integumentary setae of the preceding instars persist. There are nine pairs of spiracles, the additional two pairs being on the sixth and seventh abdominal segments. The larva of P. tristis is similar except that the thoracic tubercles occur on all three segments.
The pupae of the different species are short and robust, with the abdomen almost spherical and bearing transverse intersegmental welts similar to those of some Eucharidae.