INSECT ENEMIES OF EASTERN FORESTS 617 
the host larva, and the parasite develops internally. When feeding 
is completed the parasite pushes its way out of the host larva’s skin 
and makes its way to the extremity of the mine. It spends the winter 
as a full-grown larva in the host larva’s case or mine. Pupation takes 
place in the spring, and the adults emerge by cutting their way out. 
Pupation may occur during the summer, giving rise to two generations, 
or the larva may remain in diapause until the following spring. The 
larvae of P. nemorata bleed a little when jabbed with the ovipositor, 
and the female laps up this fluid. Often the process is repeated many 
times and larvae fed on in this manner invariably die. 
Letrastichus brevistigma Gahan is an important parasite of the elm 
leaf beetle (Galerucella wanthomelaena) wherever the beetle occurs 
throughout the Northeastern States. It had not been reared on the 
Tigi a le 
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Figure 189.—Chrysocharis laricinellae. About X 5. 
Pacific coast, however, so two shipments were sent to California for 
liberation in 1934. Later collections the same year indicated that it 
had passed through one generation in the field. The adult is about 
1 mm. long, black with a slight, metallic, greenish tinge, all coxae and 
the hind femora are mostly black, with the rest of the legs testaceous. 
Berry (28) gave an account of the species in 1938. It spends the win- 
ter as a full-grown larva within the host pupal skin. Adults emerge 
about July 1, or when host pupae first become available in the field. 
Females oviposit freely in pupae or prepupae and may begin to oviposit 
within a few minutes after emerging, whether or not mating has taken 
place. From 1 to 8 eggs are deposited at each insertion of the oviposi- 
tor, but the same pupa is often attacked more than once, and an average 
of 12 larvae develop per parasitized pupa. Females are produced in 
parthenogenesis. From 3 to 4 generations develop annually, but there 
are a considerable number of holdover larvae in each generation. In 
the vicinity of Boston, Mass., parasitization as high as 50 to 80 percent 
is common during the latter part of the season. 
