264 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



brown and the setal punctures dark. In about 20 minutes the 

 setal punctures show up black, and the cuticular nodules are 

 just beginning to be pigmented, although a hand-lens is neces- 

 sary to observe this. In about 40 minutes the body has a gen- 

 eral dullish cast, but the head, legs and prothoracic shield are 

 still bright yellow. (The legs are always a paler and more 

 translucent yellow than the rest of the body, probably because 

 they contain less adipose tissue.) In about 50 minutes the dis- 

 tal segments of the legs have a dark cast. 



The following figures refer to the time when the larva was fully 

 free from the old cuticula, and the molt complete : 10 min. body and 

 prothorax darkish, the tubercles not darker than the rest of the body, 

 head still yellow, legs duller; 20 min. no change; 30 min. body not quite 

 as dark as the prothoracic shield, distal segments of the legs blackish 

 and the other segments dull, head somewhat dull; 40 min. body about 

 the same color, head as dark as the body but not as dark as the protho- 

 racic shield ; 50 min. prothoracic shield blackish at the sides, head dull 

 darker than the body, legs still light except the distal segments; 65 min. 

 prothoracic shield dark brown ; head, legs, and tubercles brown ; general 

 aspect of the body dark yellow brown; 95 min. little if any change; 110 

 min. head black, legs dark brown the distal segments black, prothoracic 

 shield black, tubercles dark brown; 140 min. normal coloration; 

 Color description of a third instar larva, early. 



Head, prothoracic and anal shields, and legs shining black; general 

 body color very dark brown, almost black (aspect black dorsally and 

 dark dull golden yelow ventrally) ; lateral and dorsal tubercles dull 

 black; ventral tubercles brown. 

 Color description of a third instar larva, late'. 



Head, prothoracic and anal shields, and legs shining black; general 

 body color very dark brown, almost black, dorsally, very dark golden 

 yellow ventrally, much darker than earlier in the instar ; dorsal and lat- 

 eral tubercles black; ventral tubercles brown. 



THE PREPUPA. 



Formation of the pupal cell. In all insects which undergo 

 a complete metamorphosis, the wings are developed internally 

 in the larva, as hypodermal invaginations ; then a part of this 

 invagination evaginates, forming the wing-bud proper; just 

 before the formation of the pupal cuticula, this wing-bud pushes 

 out so as to lie outside the hypodermis ; finally the pupal cuti- 

 cula is secreted around it, and thus it is brought about that the 

 internal wing-bud of the larva is external in the pupa. The 

 period from the outpushing of the wing-bud in the larva until 

 the molt to the pupa is spoken of as the prepupal period. 



