Biological Papers. 139 



After carefully comparing this species with the seventeen 

 described by Ashmead in the Proceedings of the United States 

 National Museum, volume II, 1888, page 662, I am convinced 

 that we are dealing with a species that is not identical with 

 any described in that work, and I therefore append the fol- 

 lowing description, written from fully fifty males and females 

 of Lijsiphlebus sp. that had been bred from Aphis maidis: 



The male of the Lysiphlebus sp. has fifteen- jointed antennae, 

 the first and second coxae yellowish-brown to honej^-yellow, 

 third coxse being yellowish-brown to darker basally ; head and 

 thorax entirely black; petiole yellowish-brown, terminal an- 

 tennal joint equal to the preceding; antennae uniformly brown- 

 black, basal joint of hind tarsi not equal to the following. It 

 differs from all other species described by Ashmead (in the 

 above reference) in that the terminal antennae joint is equal 

 to the preceding. 



The female Lysiphlebus sp. has thirteen- jointed antennae; 

 head and thorax entirely black; first and second coxae yellow- 

 ish-brown, third yellowish-brown to darker basally; petiole 

 yellowish-brown ; hind joint of tarsi not equal to the following 

 joint, from 1-lOth to 4-lOths longer than the following, anten- 

 nae brown-black ; joints of flagellum about twice as long as thick. 



Soon after my discovery of parasitized Aphis maidis at Man- 

 hattan, the entomological department undertook the study of 

 this parasite, and it is by the courtesy of Doctor Headlee that 

 I have the privilege of using data from the experiipents per- 

 formed for the college. 



Soon after emerging the parasites copulate, occupying an 

 average of fifty-two seconds, and in some cases unite after the 

 female has deposited several of her eggs. The female runs 

 nervously about among the aphids, and when she finds one not 

 parasitized throws the tip of her abdomen underneath her 

 body between her legs, and with a quick "spring-like motion" 

 thrusts her ovipositor into the body of the aphid, leaving there 

 an egg. We then set about the determination of the length of 

 life cycle of Lysiphlebus sp., and the number of aphids a single 

 female would destroy. Twenty-five cages were set, each con- 

 sisting of a flower-pot containing a stalk of corn or sorghum 

 covered by a cloth-capped common lantern globe. From 100 

 to 200 fully grown Aphis maidis were placed on each plant and 

 a single pair of parasites introduced among them. During 

 the entire experiment reliable maximum and minimum ther- 



