APANTELES MELANOSCELUS GIPSY-MOTH PARASITE, 9 



The heart, nervous system, and silk glands are more pronounced, 

 especially the latter, which are coiled and recoiled and appear to fill 

 much of the body cavity. Traces of the tracheal system are observed 

 during the last part of the stage. 



Development is rapid and in two or three days the maggot has 

 increased in size to 4.5 mm. long and 1 mm. wide. 



The average period spent in this stage by the first-generation larva 

 is from two to three days and for the second generation from five to 

 seven clays. Just before molting the mandibles of the third-stage 

 maggot can be seen. 



THIRD-STAGE LARVA. 



The period spent by the third-stage maggot (PL I, H) within its 

 host varies from a few hours to two days with the spring generation 

 and as long as three days with the summer generation. When a 

 second-stage maggot is about ready to molt it usually works its way to 

 the central part of its host and molts there, although occasionally 

 third-stage larvse are found in the caudal end of the caterpillar. Just 

 before issuing the maggot is 5 to 7 mm, long, is slender, and tapers 

 toward the anterior end ; it is dull white and dorsally is sparsely cov- 

 ered with very fine, inconspicuous hairs. At the caudal end of the 

 body the anal vesicle is still evaginated (PI, I, H at A; PL II, F). 

 The body is apparently filled with the silk glands and has a well- 

 developed tracheal system, with eight pairs of spiracles visible. There 

 is a pair on the second segment and a pair on each of segments 4 to 

 10, inclusive. The spiracles are very tiny and difficult to determine, 

 the last seven pairs being associated with laterally protruding areas. 

 On the eleventh segment there is a slight protruding area laterally 

 which may contain a spiracle, but one was not observed on this seg- 

 ment. The mouthparts are plainly visible, consisting of labium, 

 labial palpi, labrum, maxillse, maxillary palpi, and mandibles. The 

 mandibles (PL I, L), which are 0.26 mm. long, are strong and well 

 fitted for tearing. They are slightly curved anteriorly. The tip is 

 divided into two sharp teeth. The anterior third of the mandible 

 appears to be double with two biting edges, each edge armed with 

 several teeth. There are dorsally on this part of the mandible two 

 elevations which appear to strengthen the organ. The tips and points 

 of the teeth are more heavily chitinized than the rest of the mandible. 



When ready to issue the maggot tears a hole in the side of the 

 caterpillar, usually in the fifth or sixth segment. When it has issued 

 to about two-thirds its length it begins to form its cocoon (PL II, E). 

 By the time the larva is entirely out, the anal vesicle has been in- 

 vaginatecl. If the larva is of the spring generation, it voids the 

 accumulated waste material of the larval stages after 18 to 20 

 hours in the cocoon. In about two days after completion of the 

 73070°— 22 -2 



