TENTH BE PORT OF THE STATE ENTOMOLOGIST 4:69 



Young larva. — When first hatched the larva is whitish, with a light 

 brown head. The head soon darkens and the body becomes a gray 

 color. The general appearance of the larva is that of a caterpillar 

 (PI. iii, fig. 1), though there is a strange look about it — the antennae 

 and eyes are unusually prominent. Each antenna is composed of four 

 segments; the fourth is long and slender; the third is longer, much 

 stouter and bears a special sense organ (Pi. iii, fig. 5 s). Each eye is 

 composed of a group of about twenty ocelli. A well-marked thoracic 

 shield occurs upon the first thoracic, and an irregular slightly chitinized 

 area upon the dorsum of each of the remaining body segments. The 

 most striking feature of the young larva is the row of annulated, pilose 

 spines each side of the median line on the abdominal segments, except 

 on the tenth, which bears a single median process. The spines on the 

 eighth, ninth, and tenth segments persist through all the larval stages; 

 those of the others become rudimentary after the first stage. Small 

 setae with rudimentary ones at their base occur on the body segments; 

 their relative position and number are shown in PI. iii, figs. 10, 11. 

 Spiracles occur, as in caterpillars, on the first thoracic and on the eight 

 anterior abdominal segments; they have a peculiar radiate structure 

 (PI. iii, fig. 7). The abdominal segments bearing spiracles have each a 

 l^air of rudimentary prolegs, the anterior pair being the most reduced. 

 On the last segment there is the peculiar, retractile, four-branched anal- 

 fork of Brauer (PI. iii, fig. 19). 



Rapid Growth of. Larva. 

 The larva grows rapidly during its early stages. The first stage lasts 

 five days; at the end of this time the thoracic segments become thick- 

 ened considerably; the thoracic shield and the dorsal portion of the old 

 head-case split along the median line (one was preserved in just this 

 condition), and through this rent the larva leaves its old skin in much 

 the same way as many caterpillars. Dull, apparently dead larvae were 

 repeatedly seen; in many cases this condiiion was most likely incident 

 to molting. At the end of the first stage the reduction of the annulated 

 spines on abdominal segments one to seven to mere rudiments, renders 

 the recognition of this period easy (PI. iii, fig. la). Between the other 

 stages there are less marked differences. The segmentation of the body 

 is plainer and there is also an increase in width of the head. The ratio 

 between the width of the head in the first and second stages was calcu- 

 lated, and from this was estimated, by Dyar's rule,* the width of the 



*DrAR: Psyche, v, p. 420. 1890. 



