62 



3ions. Anal shield triangular, irregularly marked with paler, its margins con- 

 vex. First and second pairs of prolegs one-third shorter than the third and fourth; 

 anal prolegs clasper-like. In locomotion the hump at the base of the abdomen is 

 scarcely noticeable. 



Tubercles much as in Stage Y; i and ii on segment IV and iii and iv on all segments 

 shining black, the others inconspicuous. On segment I the second pair are separated, 

 the posterior one much smaller, and the pair at the base of the legs are separate and 

 of equal si/e. The additional ventral tubercles present in stage Y are absent. On 

 segments II and III, tubercle iii is three times as large as i and ii; iv is minute and the 

 ventral tubercles are absent. On segments lY to IX, iii is largest, i and ii are equal, 

 and iv is farther forward. On segment lY, vi is closer to vii, and v and vi are equal. 

 On segment Y, v is smaller than vi, while iii and vii are equal. In the group, i is 

 smallest, iii a third larger, iv twice as large, and ii four times as large. On segment 

 YI, iii is just above and in front of the spiracle, and v and vi are subequal. On seg- 

 ment IX, iv is smaller and less distinct, v is farther down, near the base of the proleg, 

 and vi is just above the base of the proleg. On segment X, i, ii, v, and vi are equal, 

 iii is smaller and closer to the spiracle, iv is distant from the spiracle, and vii is four 

 times as large as viii. On segment XI, i, ii, and iii are equal, as are also iv, v, and vi; 

 iv is just behind the spiracle, with vi beneath it, and viii far down on the side of the 

 segment. On segment XII, iii is minute and more depressed, directly below^ i, and iv 

 is in the stigmatal stripe at the posterior edge of the segment. On segment XIII, 

 vii consists of 8 inconspicuous tubercles on the outer side of the anal proleg, viii 

 midway between the base and apex of the proleg on the inner side. 



POSSIBLE CAUSES OF COLOR VARIATION. 



In connection with the color variation above referred to, Mr. Girault 

 has prepared a table showing the growth and color differentiation of 

 three larvse which proved to represent the three well-marked color 

 varieties; all hatched from eggs laid by the same female (var. 

 ochracea), and were reared during September under similar conditions, 

 on cotton. 



Table XYII. — Variation in three larrx reared under similar conditions. 



Instar. 



Dark variety. 



Rose variety. 



Green variety. 



I. 



II. 



III. 



IV. 



VI. 



Normal, marked distinctly 



with deep orange. 

 Dark, marked with dull orange. 



Like the type, but lighter and 

 greenish. 



Dark, greenish, marked with 

 dull orange. 



The usual brown type; oliva- 

 ceous above with olivaceous 

 side stripes and yellow stig- 

 matals. Twenty-four hours 

 later, dorsal region lighter 

 and stripes very conspicuous. 

 Just before ecdysis, larva 

 green. 



Grayish; gray above with whit- 

 ish and yellow lines; dark, 

 the side stripes dark and the 

 stigmatals yellow. 



Normal, lemon yellow, 

 marked with dull orange. 



Pale, marked with dull 

 orange. 



Olivaceous, marked with 

 dull orange, becomingpaler 

 later. 



Ground color pale ochreous 

 marked with rust red; later 

 Avith greenish lines above 

 and conspicuous side 

 stripes. 



The usual brown tjT)e dorsal 

 region greenish 'with yel- 

 lowish lines; side stripes 

 with crimson spots, stig- 

 matals pale, margined. La- 

 ter with the crimson spots 

 more distinct. 



The usual pink type; pink 

 above the pale lines; side 

 stripes broad, velvety black; 

 stigmatals reddish yellow. 



Normal, yellowish, marked 



with deep orange. 

 Marked -with dull orange. 



Grayish, marked with dull 

 orange. 



Typical at first, but after 24 

 "hours changed to green 

 with dusky side stripes 

 and whitish stigmatals. 



Typical; side stripes brown ; 

 "later pale green with pale 

 yellow lines above and 

 darker green stripes. 

 Stigmatals pale yellow. 



The usual green type; body 

 greenish, the stripes 

 darker green and the 

 lines above pale yellow. 



