72 



RESUT.TS FROM GIPSY MOTH PARASITE LABOEATORY. 



confinement and the readiness with Avhich it attacks any snitable 

 species of caterpiHar and because the heavily chitinized chorion of 

 the egg is remarkably durable. This last fact was an advantage in 

 determining the number of eggs deposited in a caterpillar, even when 

 considerable time had elapsed after the hatching of the larva. For- 

 lunately for the success of the experiments an abundance of adults 

 of this species was at hand, reared from cocoons obtained the preced- 

 ing fall from its usual host, Th/jnmtria cunea (Drury). 



This LimniTium is one of the hymenopterous parasites alfecting 

 the fall webworm {Hyphantna cmiea) ; and although not so impoi-tant 

 as Meteorus and Apanfeh's, it is frequently found. In the northern 

 States it emerges from the fall webworm and spins its cocoon mostly 

 during the month of September. Unlike Lhmierium pUosi/hnn (Pro- 

 vancher). another sjiecies common on Ilj/phantna^ it hibernates in 



its cocoon until late 

 the following spring 

 or summer, and con- 

 sequently it has been 

 considered to have 

 only a single genera- 

 tion a year. Farther 

 south, however, as 

 pointed out by Dr. 

 L. O. Howard (1897) 

 in his bulletin on the 

 white - marked tus- 

 sock-moth {Hemero- 

 campa le iwostigma 

 Smith and Abbot), 

 of which it is an im- 

 important parasite, it 

 ji roba bly h i bern a t es 

 as an adult, as its empty cocoons were found associated with " spun- 

 up '' larVcT of the Uemcrocamjui in the middle of December, Dr. 

 Howard also records rearing the adult as early as the middle of July, 

 so that in the vicinity of Washington, D. C, two generations, if not 

 more, occur annually. Besides its favored host, Hr/phantria cunea, 

 and the Ilemeiocampa, it probably attacks other caterpillars, but so 

 far as the author is aware no other rearings have been recorded. 



Fio. ?>'2. — Limnevium ralidum : a. Adult female, side view; 

 7Jj abdomen of male ; c, metascutum from above ; il, 

 cocoon. Enlarged. (</, Ji. <1, Redrawn Irtim Howard; 

 c, original.) 



EXPERIMENTS. 

 GENERAL METHODS OF EXPERIMEXTATION. 



In most of the experiments undertaken with Limnerimn validum 

 the parasites and caterpillars were confined together in large glass 

 cylinders covered at the top witli cheesecloth, and resting on cloth- 

 covered frames. AVhen it was desirable, however, to have a large 



