INDIRECT BENEFITS DERIVED FROINI INSECTS. 263 



the former preying upon Eristalis tenax, BomhijUi, and 

 the like; 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. 



ILpipone spinipes, belonging to the family of Wasps, 

 feeds upon certain green apod larvae, of which the female 

 deposits ten or twelve with each egg. Ammojihila vul- 

 garis destroys caterpillars of a larger size, and it is pro- 

 bable that most of the other Vespoid and Sphecoid Hij- 

 menoptera, viz. Trypoxylon, PhilantJws, Larra, Crabro^ 

 S:c. assist in this great work. 



Ponqjilus, 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 Sand-wasps lend their aid. 

 One of these last, mentioned by Catesby {Pronceus, cccru- 

 leus\ has been known to seize a spider eight times its 

 own weight''. Another species of this genus, which is 

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

 difficult, one would thuik, to turn to its purpose, the all- 

 devouring Blatta or cock-roach, and is therefore one of 

 the great benefactors to mankind. When this insect 

 perceives a Blatta (called there Kakerlac and Cancrelas) 

 it stops immediately : 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 abdo- 

 men underneath it, pierces it with its fatal sting. Sure 

 of its victim, it novv walks or flies away, leaving the poison 



*Latreille, Observations nouvellcs sur Ics Hymcnoplcrcs. Annal. de 

 Mas. 11. b Nat. Hist, of Carolina, ii. 105. 



