130 PSYCHE [August 



added on each side of the middle just caudad to the spines of type no. i which were present 

 in the first instar; just mesad from the base of each protuberance which gives rise to the 

 marginal spines of type no. i on the pro- and mesothorax and on the second to ninth 

 abdominal segments arises a spine which may be either of type no. 2 or of type no. 3 ; and 

 minute side protuberances giving rise to spines of type no. i begin to appear as buds from 

 the protuberances on the margin of the pro- and mesothorax. Here and there among the 

 minute dark spines on the surface of the body are minute circular openings from which, 

 when viewed obliquely, little sac-like bodies are seen to protrude. 



Third instar (PI. 3, fig. 6) : Length varying from i mm. to 1.06 mm., the greatest width 

 from .52 to .56 mm. This instar does not differ greatly in structure from the previous one. 

 The portion of the antenna which represents the apical segment of the previous instar is 

 now indistinctly divided into two segments, the outer one being slightly shorter than the 

 inner one. The rostrum reaches to about the posterior margin of the first abdominal 

 segment. The pro- and mesothorax are proportionally broader than before and the former 

 is proportionally longer from front to rear. The protuberances which give rise to spines 

 of type no. i are now, as a rule, about twice as long as the spines. Nearly all of the 

 spines of type no. 2 of the previous instar are now present in the form of type no. 3. A 

 few spines of type no. 2 appear for the first time on the outer sides of the tibiae. The num- 

 ber of facets of the eyes has increased to eleven or twelve. A few small spines of type no. x 

 appear for the first time on the lateral margins of the pro- and mesothorax anterior to those 

 present in the previous instar, and also one or two similar ones arise from the sides of the 

 protuberances which give rise to the spines on each lateral margin of the pro- and meso- 

 thorax and of the fourth to seventh or eighth abdom.inal segments. As a rule there is one 

 which arises from the under side of each of these protuberances. Between the facets on the 

 posterior side of each eye arises a spine of type no. 3. 



Fourth instar (PI. 3, figs. 7 and 8) : Length varjing from 1,3 mm. to 1.44 mm., greatest 

 width from .74 mm. to .86 mm. The most noticeable change which takes place at the third 

 moult is the first appearance of the wing pads, which arise as curved, backward growths of 

 the sides of the mesothorax, giving this segment of the body a form suggestive of the out- 

 line of a dumbbell. The wing pads extend back on each side to a little beyond the anterior 

 margin of the first abdominal segment. The prothorax is proportionally longer than before, 

 and the facets of the ej'es are more than tAvice as numerous as before. The terminal seg- 

 ment of the antenna has not increased in length in proportion to the other segments and 

 is now about two thirds as long as the third or preceding segment. The constriction 

 between the two terminal segments is more marked than before. The rostrum reaches to 

 about the base of the abdomen. Spines of type no. 1 now arise from bases which average 

 about four times as long as the spines. A few more spines of this type have made their 

 appearance arising from the bases of those previously present on the lateral margins of the 

 pro- and mesothorax and of the fourth to seventh segments of the abdomen, and a single 

 one of the same tj-pe has arisen independently)- on the lateral margins of the pro- and meso- 

 thorax in front of those which appeared independently in previous instars. 



Fifth instar (PI. 3, fig. 9): Length var^'ing from 1.S6 mm. to 2 mm., greatest width 

 from I.I mm. to 1.36 mm. Quite a marked change in form occurs at the fourth moult, the 

 most noticeable of which is the increased length of the prothorax in proportion to the length 

 of the body and the increase in length of the wing pads. The prothorax now occupies a little 

 more than one fourth the entire length of the body. The wing pads now extend back on each 

 side a little beyond the posterior margin of the fourth abdominal segment. On the outer 



