8 BULLETIlSr 1028, U. S. DEPARTMENT OF AGEICULTURE. 



sickle-shaped mandibles (PI. I, J) , which are well fitted for tearing, 

 are plainly seen, being in motion much of the time, as the maggot 

 feeds on the lymph and fat bodies of its host. They are 0.08 mm. 

 long, are chitinized throughout, but more heavily so at the tips, and 

 form a good character for distinguishing this stage from the follow- 

 ing ones. The body is made up of ten segments at this period, but 

 later has eleven after the tenth segment divides. On the dorsum the 

 maggot has a systematic arrangement of short, rather stiff, back- 

 ward pointing spines. The spines are located as follows : Two each 

 on the second and third segments, four on the fourth segment, six 

 each on the fifth to ninth segments inclusive, and eight on the tenth 

 segment. It seems likel}' that these spines assist the maggot in 

 working itseway to the caudal end of the host. 



The anal vesicle, which is common to the microgasterine larvae, 

 is prominent and the caudal horn is seen just beneath the evaginated 

 anal vesicle. 



As the larva matures, the heart, nervous system, and silk glands 

 can be distinguished, but no evidence of the tracheal system is ap- 

 parent. 



When ready to molt the larva has increased in length to nearly 

 2 mm. and the body has widened in proportion, except the head, 

 which remains about the same width throughout the stage. 



The larva remains in this stage from two to three days in the 

 spring generation and from six to eight days in the summer genera- 

 tion. 



SECOND-STAGE LAKVA. 



In molting the head skin of the first-stage maggot is split off and 

 is occasionally found in the body cavity of the host, closely associated 

 with the cephalic region of the second-stage larva. The remainder 

 of the molt skin is worked back to the last body segment (PL I, G 

 atM). 



The second-stage maggot is usually found dorsally in the caudal 

 end of the host in the body cavity, its head toward the posterior end 

 of the caterpillar and its body resting longitudinally. Wlien first 

 molted it measures about 2.75 mm. in lengih and 0.55 mm. in width, 

 the head and body being approximately the same width. 



In contrast to the first-stage maggot the body is entirely destitute 

 of spines and the mouthparts are poorly developed. The mandibles 

 (PL I, K) are not fitted for tearing or biting, but are soft, fleshy 

 forms without chit in and are very difficult to locate. 



The anal vesicle is still present and is more prominent than in the 

 previous stage (PL I, G at A). The caudal horn is present but has 

 not groAvn with the developing maggot and appears very small in 

 comparison with the size of the larva (PL I, G at P). 



