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 days. Just before molting the mandibles of the third-stage 
maggot can be seen. 
THIKD-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 larvae 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 (PL 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, maxillae, 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- 
vaginated. 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 
