382 



AN ECONOMIC ENTOMOLOGY. 



Fig. 440. 



length, and the wings expanding fully an inch and a quarter or 

 even more. This makes the species easily recognizable, and it 

 will serve very fairly as a type of this particular branch of the 

 family. Species of this size usually lay only a single egg in the 

 host, and in the case of the "swallow-tail," the caterpillar retains 

 strength enough to change to a chrysalis ; but from this chrysalis 

 there emerges through an ugly hole in the side the Trogus exe- 

 sorius, which has just been described. Frequently, however, in 

 smaller species, a considerable number of parasitic larvae develop 

 in one caterpillar. 



Of quite a different type, as compared with those just described, 

 are the species of Ophion. These are large or very large 

 creatures, black or honey-yellow in color, and the bodies are 



transversely flattened and 

 squarely cut off at the pos- 

 terior extremity. They are 

 thus blade-like in shape, and 

 the ovipositor rests concealed 

 in a groove in the squarely 

 cut off end segment. Though 

 these insects are not stinging 

 Hymenoptera, strictly speak- 

 ing, yet the ovipositor is so 

 short and sharp that the in- 

 sects make use of it as a 

 means of defence. They 

 should be carefully handled, 

 therefore ; though the sting, 

 if * ' hot' ' for a few moments, 

 seems not to be so poisonous 

 as that of the bees and wasps. 



In the family Braco7iidcs 

 the species are smaller, as a 

 rule, — sometimes very small 

 indeed, — and all are parasites. The difference between the pre- 

 vious and the present family is in the venation, and is not easily 

 made out, except by the special student ; nor from a practical 

 stand-point is the matter an important one. It is among the 

 members of this family that we find many of the minute creatures 



Long-tailed Ophion, Ophion macrtirum, 

 larva. 



and 



