218 INSECTA. 



positor is very short, and but slightly or not at all apparent, deposit 

 their ova in the body of larvae, caterpillars, and nymphs, which are 

 exposed or very accessible. 



The larvas of the Ichneumonides, like all the others of the suc- 

 ceeding' families, are destitute of feet. Those which, in the manner 

 of intestinal worms, inhabit the bodies of larvae or caterpillars, where 

 they sometimes form communities, only attack the adipose substance 

 — corps graisseux — or such of the internal parts as are not necessary 

 to their existence. When about to become nymphs, however, they 

 perforate their skin in order to open a passage, or put them to death, 

 and there tranquilly undergo their ultimate metamorphosis. Such 

 also are the habits of those which feed on nymplis or chrysalides. 

 Nearly all of them spin a silken cocoon, in which they become nymphs. 

 These cocoons are sometimes agglomerated, either naked, or en- 

 veloped in a sort of tow or cotton, in an oval mass, frequently found 

 attached to the stems of plants. The symmetrical arrangement of 

 the cocoons of one species forms an alveolar body, resembling the 

 honeycomb of our domestic Bee. The silk of these cocoons is some- 

 times of a uniform yellow or white, and sometimes mixed with black 

 or filaments of two colours. Those of some species are suspended to 

 a leaf or tAvig, by means of a long thread. Reaumur has observed 

 that when detached from the bodies to which they are fixed, they 

 make repeated jumps to about the height of four inches, the larva 

 enclosed in the cocoon approximating the two extremities of its body, 

 and then suddenly returning to a straight line in the manner of 

 various skipping larvee of Dipterous Insects, found on old cheese. 

 This family is extremely rich in species. 



The difference in the number of joints found in the palpi may 

 serve as a basis of three principal divisions. 



The first will comprise those species in which the maxillary palpi 

 have five joints, and the labials four. The second cubital cell is very 

 small, and almost circular or null. 



We will form a first subdivision with those in Avhich the head is 

 never prolonged anteriorly in the form of a snout or rostrum, in 

 which the ligula is not deeply emarginated, and in which the max- 

 illary palpi are much elongated, their last joints, in form and pro- 

 portion, differing evidently from the j^receding ones. The ovipo- 

 sitor is not covered at base by a large lamina in the form of a 

 vomer. 



Here, this ovipositor is extremely salient. 



Some species are distinguished from the others by their almost 

 globular head, their mandibles terminated in an entire or but sliglitly 

 emarginated point, and by the elongation of their metathorax. Tlie 

 second cubital cell is frequently Avanting. Such arc those Avhich form 

 the 



Stephanus, Jur. — Pimpla, Bracox, Fab., 



Where the thorax is much thinned anteriorly, and on a level at its 

 posterior extremity Avith the origin of the abdomen, so that this part 

 of the body appears almost sessile and inserted in the posterior and 

 superior extremity of the thorax as in the Evaniee. The posterior 



