122 .MEMOIRS OF THE NATIONAL A0ADE:\IY OF SCIENCES. 



The subdorsal spines ure now nmcli slioiter tlian lieforo iuul siiiipl(> and coiiiciil; while the 

 lateral series, instead of being nearly as lono- as the dorsal ones and deeply forked, are short and 

 stout, ending- in three short, stout, piliferous spines. 



The bod\- is now dull chestnut, with dusky diseolorations, but icit/ivut the deckled hiack 

 hands and sjjoti of stage I, the body being decidedly darker. The black spiracles are surrounded 

 by a diti'use black ring-. The thoracic legs are black; the middle abdominal legs jet-black outside, 

 on a chitinized portion; the anal legs are of the color of beeswax, with a jet-black spot or wart 

 at the tip, and a dusky patch on the sides; these black plates are larger and longer than in stage f. 



The descriptions of stages III and IV were drawn up from a series reared at my request b}' 

 the late Mr. S. Lowell Elliott and preserved in alcohol: the coloi-s are described from a set of 

 drawings by Mr. Bridgham. Mr. F^Uiott observed live stages. 



stage III. — (Preserved the third day after the second molt.) Length, 30 mm.; width of the 

 head. :! nun. The head is narrow, aljout one-half as wide as the second and third thoracic seg- 

 ments; chestnut brown, with two pale, longitudinal bands in front, each band ending at the base 

 of the pale antenn;^. 'The ta-o dorsal .spines on the prothoraeic xegaient are much .shorter than in 

 stage II, with much stouter lateral spinules, and with shorter forks at the tip, and the spines on 

 the trunk are shorter. The two second thoracic dorsal spines are a little stouter than before, 

 l)ut are nearly- as in stage II, and are spinulated in the same way; they are -±.5 nun. in length; 

 they are pale on the basal half and dark brown on the distal half; the corresponding spines on 

 the third thoracic .segment are a little shorter. The dorsal and lateral .yjuu-s on aMonu'nal 

 .Segments 1-7 are much smaller in proportion than in stage 11, the dorsal spine being still unevenly 

 foi-ked. The "caudal horn" on the eighth .segment is now 3 mm. in length, and is still regularly 

 forked us before. The corresponding single median spifte on the ninth segment is jjiinute and 

 much smaller than before. The two larger spines on the suranal \A-Atc are smaller than l\ef ore, 

 each bearing four spines, and behind these on the edge of the plate are four minute conical 

 spines; the plate is regularly rounded behind; it is dark brown in the middle, with paler rounded 

 granulations. On the side of the anal legs is a similarly ornamented distim-t, n<irr(iii\ triangular 

 field not developjed in stage II. The middle abdomiiuil legs are tipped with l)lack as before. The 

 body is more hairy than before. 



The general hue of the body is at tirst pale yellowish brown (raw sienna), with a large pale 

 ana around the dark spiracles. There are no distinct markings. Toward the end of the stage 

 the body in those feeding on white pine becomes decidedly reddish, and in fact the color varies 

 from violet through all shades of golden brown and orange purple to black. The horns are rosy- 

 red at base; there is a broad, pale, diti'use, subdorsal band on each side and the dark sjjiracles are 

 rendered very conspicuous by the broad yellowish ring around them. 



Fig. o. — Armature of F.aeles imperialis. Stage I. a, a dorsal prothoracic spine; J, a sub- 

 dorsal prothoracic spine; c, a dorsal spine of the second thoracic segment; d^ a dorsal spine of 

 the third thoracic segment; r, the tirst abdominal segment, side view, showing the anterior and 

 posterior black band, and the position of the dorsal, subdorsal, and infraspiracular spines with 

 the spiracle; f\ the suranal plate, in part, bearing the anterior spine, ending in four setifei-ous 

 tultercles and the two smaller, simple spines at the end of one side of the plate; y, the "caudal 

 horn" or medio-dorsal forked spine of the eighth uromere, seen partly from the side; </', end of 

 the same, seen from in front, showing the two forks; /(. one of the dor.sal spines on the ninth 

 uromere. All drawn with the camera to the same scale. 



Fig. If,. — Armature of Fades imperialis. Stage II. '/, end of one of the dorsal j)rothoracic 

 "horns;" i, one of the dorsal second thoracic "'horns;" t', the "caudal horn,"' or medio-dorsal 

 spine on the eighth uromere. Stage III. d^ one of the second thoracic " horns;" '% the "caudal 

 horn" or medio-dorsal sj)iiie of the eighth uromere. All drawn with the camera to the same 

 scale. 



Stage 1 V. — (Four days after the third molt.) Ijcngth, 40 mm.; width of the head, 4..5 nun. 

 The characters of the full-grown larva are now nearly assumed. The head is, in one specimen, 

 twice banded with pal(^ yc^llowish in front, in another the bands are nearly obsolete and the head 



