INJURING THE LEAVES. 251 



and even deserting fields of low herbage if they can 

 find more elevated roosting points near by. When 

 very abundant, and when the weather continues dry. 

 they occasionally swarm like the Rocky Mountain 

 Locust, but rarely Hying continuously to any great 

 distance, or indeed taking any definite course." 



Fortunately there are a considerable number of 

 species of animals that depend, to a greater or less 

 extent, upon grasshoppers for subsistence. Some of 

 these are predaceous, others parasitic, but all com- 

 bine in keeping the pests in check. Prominent 

 among those efficient in this work are the species 

 that live upon or within the eggs of the locusts, as 

 the latter exist in that state for the longest period of 

 their lives, and are also then the most helpless and 

 susceptible to injury. The common blister beetles 

 (Epieauta) live, so far as known, in their larval shite, 

 exclusively upon the eggs of locusts, and are thus of 

 immense benefit to man. Small red mites, which 

 are frequently seen attached to the bodies of the ma- 

 ture locusts, are also of benefit, in that while young 

 they suck the life-juices of the locusts, and, later, 

 puncture their eggs and extract the contents. The 

 larvae of the common black ground beetles ( ( 'arabida ) 

 which are, to a great extent, carnivorous, also feed 

 upon the eggs, and, as they are everywhere abund- 

 ant, contribute not a little to lessening their num- 

 bers. Certain species of two-winged flies {Dvptera) 

 are also known to be parasitic upon the egg- as well 

 as the adults. 



