HYMENOPTERA 



921 



except for being somewhat stunted, develops normally to maturity, 

 when the nearly grown parasite larva emerges from its body and 

 finishes it off in one big meal. Ascogdster quadridentdtus was intro- 

 duced into this country from Europe to control the codlin moth. 

 Its life history is typical of the subfamily. In midsummer about 

 thirty-five days are required for a generation. Although its activities 

 are helpful, this species does not effectively control the codlin moth. 

 The Microgasterinas includes species with hairy eyes and with the 

 abdomen so short that it is surpassed by the hind femur. Except in 

 the genus Apdnteles there is a tiny cell near the center of the fore wing. 

 Most of our species have eighteen antennal segments. Microgdster, 

 Microplltis, and Apdnteles are the genera of importance. All are 

 parasitic on caterpillars. The genus Apdnteles contains nearly two 

 hundred North American species and is probably the most beneficial 

 among the braconids. Each species attacks a particular type of 

 caterpillar — leaf miners, or cutworms, or larvsi of Sphingida;, etc. 

 Many are gregarious parasites, often a hundred or more developing 

 from a single host. The female may insert ten to thirty eggs at a 

 single thrust of her ovipositor and may make several thrusts into a 

 single caterpillar. The parasite larvae all mature at exactly the same 



time and bore to the outside simul- 

 taneously. Often they spin their 

 yellow or white cocoons at the point 

 on the caterpillar from which they 

 emerged, when they look superfi- 

 cially more like eggs than cocoons 

 (Fig. 1 1 49) . Other species may spin 

 a mass of cocoons bound together 

 by more or less loose silk near the body of the caterpillar (Fig. 11 50). 

 The parasitized caterpillar lingers on for a few days 

 after the parasites have left it and finally dies. 

 The species commonly attacking sphingid larvae is 

 Apdnteles congregdtus. Apdnteles glomerdtus attacks 

 larvee of the cabbage butterfly. Through the efforts 

 of Dr. C. V. Riley this European species was intro- 

 duced and it is now widely distributed in North 

 America. Other species of Apdnteles have been 

 introduced to control the gypsy moth and the 

 European corn borer. 



The Braconinae ( = AgathidincB) includes species 

 with the cell next to the stigma extending less 

 than half-way beyond the end of the stigma to 

 the wing tip. There is a very small cell in the center 

 of the wing below the stigma. These are the bra- 

 conids most frequently collected on flowers. Many 

 of the species have black wings and the abdomen or pj 

 entire body red. Some species have elongate mouth 

 parts for reaching nectar and the head prolonged below into a sort of 

 beak. Edrinus limitdris is a black species about nine millimeters 



Fig. 1 149. — Caterpillar \\ith co- 

 coons of a braconid. 



