18 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



The egg is pure white in color, truncate-conical in form, with 

 crater like apical depression. Greatest diameter 0.79 to 0.83 mm. 

 height, 0.79 to 0.8 mm.; diameter of entrance to apical cavity, 

 0.13 mm.; edges ragged. Surface of eggs marked with slightly 

 depressed reticulations forming polygonal cells, small at base of 

 the eggs and gradually increasing in size as the diameter of the egg 

 decreases. About 52 cells occur around largest circumference 

 and about 21 cells around smallest circumference. As the embryo 

 develops the egg gradually becomes distinctly pinkish. 



The pupa is robust measuring about 10 mm. in length, and 5 

 mm. in width. Its color is light brown with dark brown spiracles. 



The full grown larva is about 25 mm. in length, 5 mm. in diam- 

 eter and cylindrical in general form. The head and cervical 

 shield are 3 r ellowish brown in color as is also the anal shield. The 

 spiracles are jet black. Integument marked with a rather broad 

 stripe of deep pink extending along each side of the body inter- 

 rupted at the joints. This stripe shades to paler pink above. 

 Dorsal organ greenish and conspicuous. Where integumental color 

 is absent or pale the body fluid and internal organs give greenish 

 tone. In the younger stages the larvae are more distinctly pinkish 

 in color and lack the green tinge. 



The eggs are deposited exclusively, as far as observed, on the 

 tips of the involucral bracts and of the leaf lobes. Of 40 specimens 

 of eggs 35 were found to occur singly. The exceptions consisted 

 of one group of three and one group of two eggs. 



The larva does not eat the egg shell after emergence nor has it 

 been found feeding except upon the squares and bolls. Into these 

 parts it eats its way exhibiting feeding habits quite similar to those 

 of the cotton boll worm (Pleliothis obsoleta). The young larva eats 

 into several of the squares and finally attacks a boll and finishes 

 growth inside of one. No observations have been made showing 

 the number of bolls a single larva may destroy. The stems which 

 bear the damaged boll are fastened to the plant by a band of silk 

 apparently spun by the larva as it approaches the boll. This is 

 strong enough to hold the boll if the stem should become detached 

 as it sometimes does, but it seems probable that there is some other 

 purpose in this action. The entrance to the cotton boll is made 

 almost invariably near the base between the bracts. It is 2.25 

 and 3 mm. in diameter in the specimens observed. 



When placed together the worms do not show cannibalistic 

 tendencies. Sixteen out of nineteen worms under observation 

 removed from the bolls which they had completely eaten out, 

 burrowed into the ground without hesitation. Pupal cells thinly 

 lined with silk were constructed at depths of from one to three 

 inches below the surface. The Thurberia boll worms appear to 



