946 AN INTRODUCTION TO ENTOMOLOGY 



nests of Ceratlna dupla, the little carpenter bee. Eurytoma is a large 

 genus parasitic on many types of insects. A few species infest seeds. 

 Recent revisions of United States species are : Harmolita, Proc. U. S. 

 Nat. Mus. 1919, 55:433-471; Decatoma, Proc. U. S. Nat. Mus. 

 1932, vol. 79, art. 28, 95 pages. For an account of the seed-infesting 

 species see Crosby ('09). 



Subfamily ENCYRTIN^ 



This is a large and diverse group parasitic on many kinds of 

 insects. It can be recognized by the broad mesopleurum without the 

 usual groove for the femur and by the large heavy spur on the middle 

 tibia. This spur is used in jumping. Many parasitize Coccidce, 

 Aphidse, and Aleyrodidse. At least four highly successful cases of 

 biological control are due to the introduction of these insects to para- 

 sitize scale insects or mealy bugs. 



Polyembryony is a common phenomenon in the Encyrtinse and 

 reaches its highest development in this group. The eggs of the poly- 

 embryonic species are inserted into those of Lepidoptera. The para- 

 site larvae mature in the host caterpillar just before it pupates. 

 Copidosoma truncatellum is a common parasite of Autographa hrassiccB, 

 the cabbage looper. The female lays one or two eggs into the egg of 

 Autographa. Usually the second egg deposited is without a sperm 

 and is therefore unfertilized. Each egg develops inside the growing 

 host caterpillar into hundreds of parasite larvae. The fertilized egg 

 produces female larvas and the unfertilized egg produces male larvae. 

 Beside these sexual larvae which mature into adults, there are many 

 sexless larvae in which the reproductive and respiratory systems are 

 not developed. These die without maturing. The host larva is 

 usually much larger than an unparasitized caterpillar and somewhat 

 more sluggish. Just before pupation it is killed by its parasites which 

 by that time practically fill its body. The parasite lar\^ae pupate in 

 the skin of their host and emerge as adults through holes cut to the 

 outside. Twelve hundred to three thousand may develop in a host. 

 A single egg usually gives rise to about one thousand adults. 



Some Encyrtinae have the body rather long and narrow, the disc 

 of the mesonotum more or less concave, and notauli present. These 

 are often put in a separate subfamily, the Eupelminae. The species 

 are mostly egg parasites or secondary parasites. They are good 

 jumpers, and their peculiar ability to turn both the head and abdomen 

 back over the thorax seems to be used to help them leap much as the 

 click beetles use the movable prothorax for this purpose. Many 

 have short wings with a joint at the middle so that they can be folded 

 upwards when the abdomen is raised. 



Subfamily CLEONYMIN^ 



This is a relatively small heterogeneous group that is probably 

 polyphyletic. The species that have been reared are mostly from 

 Coleoptera. 



