INDIRECT BENEFITS DERIVED FROM INSECTS. 225 



their little visiters were emigrants from the neighbouring 

 hop-grounds, where in their larva state each had slain his 

 thousands and tens of thousands of the Aphis, which, under 

 the name of the Ffy, so frequently blasts the hopes of the 

 hop-grower. It is fortunate that in most countries the chil- 

 dren have taken these friendly Coccinell^ under their pro- 

 tection. In France they regard them as sacred to the Virgin, 

 and call them Vaches a Dieu, Betes de la Vierge, &c. ; and 

 with us, commiseration for the hard fate of a mother, whose 

 " house is on fire and children at home," insures them kind 

 treatment and liberty. Even the hop-growers are becoming 

 sensible of their services, and, as I am informed, hire boys to 

 prevent birds from destroying them. If we could but dis- 

 cover a mode of increasing these insects at will, we might not 

 only, as Dr. Darwin has suggested, clear our hot-houses of 

 Aphides by their means, but render our crops of hops much 

 more certain than they now are. Even without this know- 

 ledge nothing is more easy, as I have experienced, than to 

 clear a plant or small tree by placing upon it several larvas of 

 Coccinellae or of aphidivorous flies collected from less valuable 

 vegetables. 



Lastly, to close this list of imparasitic insectivorous larvae, 

 I may mention those of Geoffrey's genus Volucella, so remark- 

 able for their radiated anus, which live in the nests of humble 

 bees ( V, bomhylans^, braving the fury of their stings and 

 devouring their young ; those of another species of the same 

 genus ( V. zonaria Meig.), which MM. de St. Forgeau and 

 Serville have ascertained to live in wasps' nests and destroy 

 great numbers of their larvae ^ ; and the ant-lion (Myrmeleori) 

 and Reaumur's improperly named worm-lion {Leptis), whose 

 singular stratagems will be detailed in a subsequent letter, 

 both of which destroy numerous insects that are so unfortunate 

 as to fall into their toils. 



The 'parasitic larva3, an extremely numerous tribe, must 

 next be considered. These chiefly belong to the order 

 Hymenoptera, and were included by Linne under his vast 

 genus Ichneumon, so named from the analogy between their 



VOL. I. 



Macquart, Dipteres, i. 482. 



Q 



