202 . HYMENOPTERA. 



form Polynema ovulorum Linu. lays numerous eggs in a single 

 butterfly's egg. 



In Anaphes the male auteunoe are twelve-jointed, those of 

 the female* nine-jointed, and the abdomen is subsessile and 

 ovoid. In Anagrus the male antennae are thirteen-jointed, 

 those of the female nine-jointed, while the tarsi are four-jointed, 

 and the acutely conical abdomen is sessile. No native species 

 are known. 



The smallest Hymenopterous insect known, if not the most 

 minute of all insects, is the Pteratomus Putnamii Pack. (Plate 

 3, figs. 8, 8a, hind wing), which we first discovered on the 

 body of an Anthophorabia in the minute eggs of which it is 

 undoubtedly parasitic. It difiers from Anagrus in the obtusely 

 conical abdomen, and the narrower, very linear wings, which 

 are edged Avith a fringe of long, curved hairs, giving them a 

 •gi'aceful, feathery appearance. The fore-wings are fissured, 

 a very interesting fact, since it shows the tendency of the 

 wings of a low Hymenopterous insect to be fissured like 

 those of Pterophorus and Alucita, the two lowest Lepidop- 

 terous genera. It is one-ninetieth of an inch in length. 



CiiALCiDiD.E Westwood. This is a group of great extent ; 

 the species are of small size ; they are often of shiny colors, as 

 the name of the principal genus im])lies, being either bronzen 

 or metallic. They have also elbowed antennaj with from six 

 to fourteen joints, and the wings are often deficient in veins. 

 In some genera, including Chalcis, the hind thighs are thickened 

 for leapiug. The ditterences between the sexes, generally very 

 marked in Hymenoptera, are here especially so. The abdo- 

 men is usually seven-jointed in the male and six-jointed in the 

 female, the other rings being aborted. The male of several 

 species has the joints of the antennae swelled and furnished with 

 long hairs above. Some of the species of Pteromalus are wing- 

 less, and closely resemble ants. They infest eggs and larvae. 

 Some species prey upon the Aphides, others lay their eggs in 

 the nests of wasps and bees. One species is known in Europe 

 to be a parasite of the common house-fl}'. Others consume 

 the larvae of the Hessian-fly, and those Cecidomyiai that pro- 

 duce galls, and also the true gall-flies (Cynips). Some are 



