BENEFICIAL INSECTS, PREDACEOUS AND PARASITIC 15 



abdomen exposed, has been noticed on the plants eating the 

 eggs and young larva) of this old potato pest. 



Another valuable species is one called by Dr. Riley the 

 Murkey Ground-beetle (Harpalus caliginosus). Its larva is of 

 considerable assistance to fruit-growers by eating large numbers 

 of curculio larv which it secures from the plums after they 

 have fallen to the earth. From a glance at its formidable jaws, 

 Fig. 10 b c, it is easy to conjecture the fate of many a curculio grub. 

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

 not foes, worthy of all the protection that can be afforded 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 pmlacmus upon them, many 

 more succumb to those minute forms which live parasitically 

 within them. A few 

 of these parasites be- 

 long to the order Dip- 

 tera, or true flies, but 

 most of them are classed 

 in the order Hymeno- 

 ptera, in which order are 

 also included the saw- 

 flies, ants, wasps, and 

 bees. 



Of the half-dozen 

 families of hymenopter- 

 ous parasites one of the 

 largest and most bene- 

 ficial is that of the 

 Ichneumon-flies. The illustrations will best show the form and 

 structure of these insects, which the casual observer will hardly 

 be able to distinguish from other families of the group. But 

 it will be noticed that the fine veins of the wings vary considerably 

 in the different parasites figured and it is by these that the 

 entomologist is enabled to separate the different groups and 

 often to identify the species at a glance. Both this and the f ollow- 



FIG. 11. Maggots of Pimpla inquisitor, a 

 parasitic Ichneumon-fly, feeding on a cater- 

 pillar which had spun its cocoon and was 

 ready to pupate. 



