INDIRECT BENEFITS DERIVED FROM INSECTS. 263 



prived of power to make resistance, seizes it again by 

 the head, and drags it away, walking; backwards, to 

 deposit it in a hole or chink of a wall^. 



Grasshoppers are the prey of another Amraophila, 

 supposed to be the Sphex pet2s?/lrarJca of Linn^, a na- 

 tive of North America, each of which in its larva state 

 devours three of a large green species with which its 

 mother has provided it ^. 



From none of the imparasitic insectivorous larvae do 

 we derive more advantage than from those which de- 

 vour the destructive Aphides, whose ravages, as we 

 have seen above, are more detrimental to us in this 

 island than those of any other insect. A great variety of 

 species, of different orders and genera, are employed to 

 keep them w ithin due limits. There is a beautiful genus 

 of four- winged flies, whose wings resemble the finest 

 lace, and whose eyes are often as brilliant as burnished 

 metals (IIemerobms,lj'mn.), the larvae of which, Reau- 

 mur, from their being insatiable devourers of them, has 

 named the lions of the Aphides. The singular pedun- 

 culated eggs from which these larvae proceed I shall 

 describe when we come to treat upon the eggs of insects ; 

 the larvae themselves are furnished with a pair of long 

 crooked mandibles resembling horns, which terminate 

 in a sharp point, and like those of the ant-lion are per- 

 forated, serving the insect instead of a mouth; for 

 through this orifice the nutriment passes down into the 

 stomach. When amongst the Aphides, like wolves in 

 a sheep-fold, they make dreadful havoc : half a minute 

 suifices them to suck the largest; and the individuals of 



* Rpaiim.v;.282. St, Pierre's Voyage,12. 

 " Bartram in Phi'os. Trawi. \Wi. 126. 



