'2(30 INDIRECT BENEFITS DERIVED FROM INSECTS. 



the former preying upon Elophilus tenax, Bombylii, and 

 the like a ; the latter amongst others ridding us of the 

 troublesome Stomoxys calcitrant. One of these last I have 

 observed stationed on dung watching for flies, which, 

 when seized, she carried to her burrow. 



Vespa spinipes feeds upon certain green apod larvae, of 

 which the female deposits ten or twelve with each egg. 

 Ammophila vulgaris destroys caterpillars of a larger size ; 

 and it is probable that most of the other Vespoid and 

 Sphecoid Hymenoptera, viz. Trypoxylon, Phiianthus, Lar- 

 ra, Crabro, &c assist in this great work. 



Pompilus, to which genus probably several species men- 

 tioned by Reaumur as preying on these insects should be 

 referred, has it in charge to keep the number of spiders 

 within due bounds : and some Ammophihe lend their aid. 

 One of these last, mentioned by Catesby (Sphex carulea, 

 Linn.), has been known to seize a spider eight times 

 its own weight 11 . Another species of this genus, which 

 is common in the Isle of France, attacks an insect still 

 more difficult, one would think, to turn to its purpose, the 

 all-devouring Blatta, and is therefore one of the great be- 

 nefactors to mankind. When this insect perceives a 

 Blatta ( called there Kakerlac and Cancrelas) it stops im- 

 mediately : both animals eye each other ; but in an instant 

 the sand-wasp darts upon its prey, seizes it by the muzzle 

 with its strong jaws, and bending its abdomen underneath 

 it, pierces it with its fatal sting. Sure of its victim, it now 

 walks or flies away, leaving the poison to work its effect ; 

 but in a short time returns, and, finding it deprived of 



a Latreille, Observation,! nouvellcs sur les Hymenoptcrex. Annal. de 

 Mm - 1] - '' Nat. Hist, of Carolina, ii. 105. 



