SCIENTIFIC SURVEY. 



159 



thickened fur leaping. The differences between the sexes, gener- 

 ally very marked in hymenoptera, are here especially so. The male 

 of Eurytoma has the joints of the antennas swelled and furnished 

 with long hairs above. Some of the species, such as those of 

 Pteromalus, are wingless, 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 consume the intestines of the 

 common House Fly. Others consume the larvae of the Hessian 

 fly, and those Cecidomyice that produce galls, and also the true gall 

 flies (Gynips.) Some are parasites on other Ichneunion parasites, 

 as there are species preying on the genus Aphidius, which is a 

 parasite on the Aphis. So also in Illinois a species of Hocke7'ia 

 and of Glyphe are parasitic on a Microgasier, which preys upon the 

 Army worm ; and Chalets alhifrons, Walsh, was bred from the 

 cocoons of Fezomachus, an Ichneumon parasite of the same cater- 

 pillar. • 



The genus Leucospis is of large size and known by having the 

 ovipositor laid upon the upper surface of the abdomen, and by its 

 resemblance to wasps. Eivrytoma hordei (fig. 6,) is found in gall- 

 like- swellings of wheat stalks. The pupas of ^'^'- ^• 

 this family have often the limbs and wings 

 soldered together as in lepidox)iera, and the 

 larvae seldom spin a silken compact cocoon as 

 in the succeeding family. We haveprobab y 

 in this country a thousand species of these 

 small parasites, nearly twelve hundred having 

 been named and described in England alone. They are generally 

 large enough to be pinned or stuck upon cards; some individuals 

 should be preserved in this way, others, as wet specimens. 



Ichneumdnidce. The Ichneumon-fly (Fig. 7,) represents the most 

 extensive family of the suborder as re- Fig;. 7. 



gards numbers. They are long and nar- 

 row bodied, with long and straight an- 

 tennai ; the ovipositor is generally long 

 and protected by two sheath-pieces of 

 the same length. In those genera that 

 have the ovipositor short, the eggs are 

 placed in exposed larvae, while those 

 provided with longer ones, such as in the 

 figure, are adapted for penetrating into 



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