36 INSECTS INMURIOUS TO STAPLE CROPS. 



in as many minutes. When the larva is ready to pupate 

 it attaches itself to a leaf, and- the larval skin dries up and 

 forms a case or puparium inside of which the pupa remains 

 until it transforms to the adult fly. 



Though most of these larvae feed upon plant-lice upon 

 the leaves, one of them, the Root - louse Syrphus - fly 

 {Pipiza radicans), lives entirely underground during that 

 stage, and feeds upon the root-lice of the apple and the 

 grape. None of this family are injurious, and as a large 

 portion of them are so beneficial as to frequently destroy 

 whole broods of plant-lice, they should not be disturbed 

 in their good work if possible to avoid it. 



The Ground-beetles. 



If, as you scrape away the loose chips at the base of a 

 tree in your door-yard, turn over an old log in the wood- 

 land, or pick up a fallen fence-rail, you will scrutinize the 

 inhabitants under these shelters, a number of shining 

 black beetles varying in length from one-fourth to one and 

 one-half inches will usually be noticed. If the city reader 

 be not so fortunate as to be fa-miliar with or have access 

 to these hiding-places, he may find large numbers of the 

 beetles under any electric arc light during the warm 

 summer evenings; for there they are having a sumptuous 

 banquet upon the small flies and moths attracted by the 

 glare. They are rarely seen at large during the day, as 

 they are almost exclusively nocturnal insects, and from 

 their habit of remaining almost entirely in or on the 

 ground they are usually known as '^Ground-beetles.'' 

 As might therefore be inferred, they are exceedingly 

 valuable to the farmer by destroying large numbers of 

 noxious insects which ])ass a part or all of their existence 



