SUBY-TAILED FLIES. Ill 



olack insect, measuring less than an inch across the fore wings, 

 with a very small abdomen on a long petiole, and enormous hind 

 legs, nearly twice as long as the whole body. On the other hand, 

 several other genera are remarkable for the extraordinary length 

 of the abdomen of the female ; thus the North American Pelednus 

 Politurator, Drury, is a shining black insect, measuring about an 

 inch and a half across the wings ; but the abdomen is very slender, 

 and composed of very long joints, the last only being short and 

 pointed; the entire insect not measuring much less than three 

 inches in length. The hind legs are also long, and the tibiae dilated. 



FAMILY VII. Chrysididce. 



Body nearly cylindrical ; abdomen with a very short peduncle, 

 and composed of from three to five segments, one of which is often 

 much larger than the others, and the last of which is often fur- 

 nished at the extremity with a series of large teeth, varying in 

 number according to the species; the terminal segments of the 

 abdomen form a retractile tube, furnished at the extremity with a 

 small imperfect sting; and the body is hard, and the abdomen 

 concave beneath, so that the insect, when alarmed, doubles its 

 abdomen beneath it, and rolls itself up into a more or less globular 

 form. 



The Euby-tailed Flies are among the most brilliant of all the 

 Hymenoptera, most of the species being either of an intense green, 

 blue, or fiery red. They are small or moderate-sized insects, 

 which are found on walls or flowers in the full heat of the sun ; 

 for, as a rule, the most brilliantly coloured insects are diurnal in 

 their habits. As far as their habits are known, they deposit their 

 eggs in the nests of other insects (chiefly Hymenoptera), on the 

 larvae of which their own offspring feed. The European species 

 are very numerous, and are divided into a considerable number of 

 genera; but it is some years since anything of importance has 

 been published on the exotic Chrysididce. Chrysis Ignita, Linn., the 

 commonest of the European species, varies very much in size and 

 colour, as well as in the length and position of the four teeth at 

 the extremity of the abdomen. It is either blue or green, or 

 suffused with copper, or even considerably varied with black. 

 The late Mr. F. Smith suggests that its extraordinary variability 

 may be due to variation in food, as it is parasitic on several genera 

 of Hymenoptera of different sizes and habits (Vespa, Odynerus, 

 Cerceris, etc.). 



