512 



NATURAL HISTORY OF ARTHROPODS. 



FIG. 638. My mar pulchellus. 



studied or collected with the same assiduity which has marked the study of the Chal- 

 cididae, and less than seven hundred European species have thus far been described, 

 yet there is reason to believe that this group is nearly as rich in species as the family 

 we have just considered. 



In point of size of body, the Proctotrupidae are in general the smallest of the 



Hymenoptera. The largest species rarely exceed 

 4 mm. in length, while the sub-family Mymarinse 

 contains the smallest insects known, Alaptus exci- 

 sus, measuring only 0.17 mm. (betAveen six and seven 

 thousandths of an inch). Mijmar pidchellus is about 

 a fiftieth of an inch in length. In shape, the body 

 is slender, and the color is almost invariably black or 

 brown without metallic lustre. The head is fre- 

 quently carried in the same plane with the body. 

 The antennae are usually long and slender, in the 

 males of some species exceeding the whole body in 

 length. The wings are often wanting, and when present are entirely veinless, or they 

 may approach (as in Telenomus) the venation of some of the Chalcididaa, or (as in 

 Chelogynus) some of the Braconidae. 



In habits the Proctotrupidae are nearly all parasitic. Many species of the sub- 

 family Scelioninoe live in the eggs of other insects. Teleas and Telenomus are often 

 parasitic upon lepidopterous and heter- 

 opterous eggs, Prosacantha upon cole- 

 opterous, and JBceonura upon the egg 

 masses of orthoptera. Many species are 

 internal parasites of other larvae, and 

 many others are secondary parasites, 

 that is, parasites upon species of the 

 other closely related entomophagous 

 families. Others again are external 

 feeders ; thus, the larvae of the curious 

 genus Gonatopus are found fastened under the wings of leaf-hoppers. A few species 

 are inquilines, but none, so far as we know, are plant feeders. 



The family BRACONID.E is the Ichneurnonides adsciti of authors. Under the popu- 

 lar name ichneumon-flies are classed the members of one of the most extensive groups 

 of insects, a group including several thousand described species. By many this 

 entire group is considered as constituting a single family, the Ichneumonidae. The 

 species of this group may be recognized by the following character. The abdomen is 

 attached to the thorax at its hinder extremity and between the bases of the posterior 

 coxae. The wings are veined, the anterior pair always exhibiting perfect cells upon 

 their disc. The ovipositor is straight and often exserted. The antenna? are nearly 

 always filiform or setaceous, and composed, except in a few small Braconids, of more 

 than sixteen joints. 



The larvae are soft, fleshy, cylindrical, footless grubs. They are parasites, usually 

 infesting the larvae of other insects. Apparently no insect is safe from their attacks 

 in however protected a place it may live. Even species which live within solid wood 

 and those which inhabit water become their victims. They do not even spare the 

 members of their own family. We thus find secondary and sometimes tertiary para- 



FIG. 639. , Telens lieriusrtilus : b, Teleas ovipositing 

 in other eggs. 



