100 



MEMOIRS NATIONAL ACADEMY OF SCIENCES. 



Vol. XII, 



Fig. 2. — Automeris io. 



showing the eversible glands (a), etc. 



After molting, July 28. — Length, 17 to 18 mm. The spinules on the spines are mostly 

 whitish (those at the ends black), giving a grayish appearance to the larva. Head reddish 

 amber; body, reddish-yellow. 



Larva after another molt, August 6. — Length, 30 to 35 mm. As soon as the old skin is cast, 

 and while the parts are limp and soft, the spines present a curious appearance; the spinules 

 being short, and placed close together, so that the whole spine forms an elongated conical mass. 



Soon the spinules stand out and the larva presents the 

 normal appearance. It is now much lighter than before, 

 all the spines being dense and pale, but afterwards they 

 become wholly black or black at the ends, including the 

 hairs, though the general effect of the mass of spines is to 

 give a pale horn-colored yellowish-green hue to the body. 

 Color of the body as before, but there is a distinct broad 

 a ireshiy hatched larva, deep oran g e spiracular line, edged slightly above, and 

 broadly below, with whitish. The head is blackish in front, 

 with a whitish V-shaped mark and a whitish dash in the middle of the V or clypeus; labrum 

 whitish. 



Full-fed larva, molted August 16 to 20. — Same characters as before the last molt, only 

 differing in being much larger. Body cylindrical, with stout spinulated spines arising in whorls 

 from small conical tubercles, arranged in seven rows on the thoracic and five rows on the abdom- 

 inal segments; the spinules at tip very sharp and poisonous, often ending in a stiff hair; 

 about twelve spinules on each tubercle, some of the lateral abdominal thoracic spinules tipped 

 with black. Head of the usual size, rather large, pea-green; the eyes, except the posterior 

 one, situated on a black spot; labrum pale amber. Body and spines pea-green. On the 

 abdominal segments is a lateral broad bright reddish spiracular band, broadly edged with white 

 below; this line extends to the end of the outer 

 side of the anal legs. Spiracles whitish, narrowly 

 edged with black; ends of the abdominal legs and 

 entire thoracic legs reddish. Length, 60 mm. 



Larvae were found on beech at Jackson, 

 N. H, September 10. 



[The following account of the transforma- 

 tions of A. io appeared in Proc. Amer. Philo- 

 sophical Society, XXXI (1893), pp. 168-171:] 



At Brunswick, Me., the eggs were laid in confinement, 

 June 5-7, and the larvse hatched June 25, or about three 

 weeks afterwards. Another year, larvse in the second stage 

 were observed July 16. For an excellent but brief descrip- 

 tion of all the stages see Riley's Fifth Rep. Ins. Missouri, 

 135; also Lintner's Entomological Contributions, II, 146. 

 Both authors state that there are six stages. 



Egg. — 1.8 mm.; width, 1.4 mm. It is regularly oval- 

 cylindrical in form and slightly flattened; yellow during 

 early embryonic life, with sometimes an orange spot on each 

 side. Under a high-power triplet the surface of the shell 

 is seen to be very finely granulated (not smooth and 

 shining), and under a one-half-inch objective the surface 

 is seen to be divided into close-set, very small, slightly 

 raised but flattened areas, separated by narrow valleys; the areaB are very irregular, but often are somewhat polygonal 

 in outline. 



Larva. — Stage I. Length, 5.5, when freshly hatched; the head, 0.8 mm. in width. The body is uniformly yellow- 

 ish brown; the head and spines are dark, blackish brown. All the feet, both thoracic and abdominal, are of the same 

 color as the body. The spines are in four rows, i. e., there are eight on each segment, except on those bearing the 

 abdominal legs, when the smallest or infraspiracular ones are wanting. The eversible glands are well developed; a 

 pair on the first and a second pair on the seventh abdominal segment; they are situated behind the spiracla of their 

 Begment and between the subdorsal and spiracular row of spines. The spiracles are very small and hard to detect in 



Fig. 3. — Automeris io. 



Armature of the three thoracic segments, 

 stage I. 



