GENERAL ZOOLOGY 



Closely allied to the gall-flies are the ichneumon-flies, one 

 of which, O'phion, is shown in Fig. 49. This species deposits 

 its eggs in the burrows of a wood-boring larva by means of its 

 long ovipositor, and the ichneumon larva on hatching moves 

 along in its burrow until it finds its host, when it fastens 

 itself to it and destroys it by sucking its blood. This carniv- 

 orous habit may be regarded as an approach to parasitism. 

 Many of the ichneumon-flies are true parasites in the larval 

 stage, the eggs being deposited on the skin or in the body 



FIG. 49. Ichneumon-Fly. Natural size 



of the caterpillars, upon the fluids of which the ichneumon 

 larva feeds. The pupal stage is generally passed within the 

 body of its victim. 



Saw-Flies. The saw-flies differ from all the insects so far 

 discussed in this chapter in having the base of the abdomen 

 as broad as the thorax. The ovipositor of the female consists 

 of a pair of saws, which are used to make slits in the leaves 

 and stems of plants, in which she deposits her eggs. Fig. 50 

 shows the American saw-fly (Cim'bex america! no) , our largest 

 species. The larva looks like the caterpillar of a butterfly or 

 moth, but has more legs. It has the curious habit of coiling 

 the posterior end of its body about a branch, as shown in the 

 illustration. It forms a brown cocoon in which the winter is 

 passed in the ground. An Australian saw-fly is credited with 

 staying with its eggs till they hatch, afterwards brooding over 

 the young with outstretched legs, and protecting them by all 

 the means in her power. 



