ORDER ETMENOPTERA. 



169 



Family Braconidse. The species of this numerous group differ from 

 the Ichneumonidae in slight re- 

 spects, i.e., in " the absence of the 

 second recurrent vein of the fore 

 wings, and by having the first sub- 

 marginal cell generally, though not 

 always, separated from the first 

 discoidal cell, and, with the excep- 

 tion of one sub-family, the Aphi- 

 diuse, by the non-existence of a 

 real articulation between the 

 second and third abdominal seg- 

 ments" (Cresson). In their habits 

 and general appearance they do not 

 differ from ordinary Ichneumon- 

 ids, though, as a rule, of smaller 

 size. The group is represented by 

 Bracon and Microgaster; the 

 species of the latter spin their 

 cylindrical cocoons either within 

 the bodies of caterpillars, or fasten 

 them in a thick mass to the ex- 

 terior. The species of Aphidius 

 are parasitic in Aphides. 



Family Chalcididae. The fore 

 wings are nearly veinless; the pos- 

 terior margin of the prothorax not 

 reaching the tegulae; while the 

 ovipositor issues from before the 

 end of the abdomen. The Chal- 

 cids are generally minute: many of 

 them of beautiful shades of green, 

 with metallic reflections. A 

 goodly proportion of them are 

 secondary parasites, viz., are parasitic on other Chalcids; some de- 

 posit their eggs in galls. Typical genera are Pteromalus (P. pupa- 

 rum Linn., Fig. 214), Serniotellus, and Chalcis. Eurytoma Twrdei 

 Harris is the wheat joint- worm, not being carnivorous. 

 Family Proctotrupidae. In these minute egg-parasites, as many of 

 them are, the protborax extends to the tegulse, and 

 the ovipositor issues from the end or apex of the ab- 

 domen. The wings are also almost veinless, and in 

 the minuter forms they are lobed or fissured with 

 long fringes. Many species, as those of Mymar, 

 Teleas, and Platygaster (Fig. 215), lay their eggs in 

 those of other insects, and hence they are the mi- 

 of nutest of Hymenoptera. Pteraiomus puimimi Pack. 



is but one-ninetieth of an inch long. 

 Family Pelecinidae. In the single genus representing this group 

 the antennae are long,. not elbowed, and thread-like; and the male 

 abdomen is clavate, while that of the female is remarkably long and 

 slender. Pelecinus polycerator Drury. 



I 



FIG. 214. Parasite of the cabbage 

 butterfly, a, male; 6, female; c, 

 larva; d, pupa. 



FIR 215. 

 parasite 

 canker-worm. 



