BEITEFICIAL INSECTS, PKEUACEOUS AND PARASITIC. 39 



Murky Ground-beetle {Harpalus caligiiioms). Its larva 

 is of considerable assistance to fruit-growers by eating large 

 numbers of Curculio larvae, which it secures from the 

 plums after tliey have fallen to the earth. From a glance 



Fig. 20.—^, larva of Murky Ground-beetle; B head of same; G , 



mandible. 



at its formidable jaws. Fig. 20, h-c, it is easy to conjec- 

 ture the fate of man}^ a curculio grub. 



Thus here again are found some " bugs '' that are friends 

 and not foes, worthy of all the protection that can be 

 aiforded them, and well repaying such careful observation 

 of their habits as may be bestowed upon them. 



Insect Parasites. 



Though large numbers of injurious insects are annually 

 destroyed by those which are purely predaceous upon 

 them, many more succumb to those minute forms which 

 live parasitically within them. A few of these parasites 

 belong to the order Diptern, or true flies, but most of them 

 are classed in the order Hymenoptera, in which order are 

 also included the saw-flies, ants, wasps, and bees. 



Of the half-dozen families of hymenopterous parasites 

 one of the largest and most beneficial is that of the 

 Ichneumon-flies. The illustrations will best show the 

 form and structure of these insects, which the casual 



