INDIRECT BENEFITS DERIVED FROM INSECTS. 197 



touches one, which he immediately transfixes with his trident, elevates into 

 the air, that he may not be disturbed by its struggles, and soon devours. 

 The havoc which these grubs make amongst the Aphides is astonishing. 

 It was but last week that 1 observed the top of every young shoot of the 

 currant-trees in my garden curled up by myriads of these insects. On 

 examining them this day, not an individual remained ; but beneath each 

 leaf are three or four full-fed larvae of aphidivorous flies, surrounded with 

 heaps of the skins of the slain, the trophies of their successful warfare; 

 and the young shoots, whose progress has been entirely checked by the 

 abstraction of sap, are again expanding vigorously. 



But even these serviceable insects must yield the palm to the lady-bird 

 or lady-cow (^Coccinella) , the favorite of our childhood, which, as well as 

 most of its congenors, in the larva state, feeds entirely on Aj^hides^ ; and 

 the havoc made amongst them may be conceived from the myriads upon 

 myriads of these little interesting animals, which are often to be seen 

 in years when the plant-louse abounds. In 1807 the shore at Brighton, 

 and all the watering-places on the south coast, was literally covered with 

 them, to the great surprise, and even alarm, of the inhabitants, who were 

 ignorant that their little visitors were emigrants from the neighboring 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 Fli/, so frequently 

 blasts the hopes of the hop-grower. It is fortunate that in most countries 

 the children have taken these friendly Coccinellae under their protection. 



In France they regard them as sacred to the Virgin, and call them 

 Vaches a Dieu, Betes de lay 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 discover 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 knowledge nothing is more easy, as I have experienced, than to clear 

 a plant or small tree by placing upon it several larvae of Coccinellae or of 

 aphidivorous flies collected from less valuable vegetables. 



Lastly, to close this list of im parasitic insectivorous larvae, I may mention 

 those of Geoffrey's genus Volucella, so remarkable for their radiated anus, 

 which live in the nests of humble bees {V. bombylans), braving the fury 

 of their stings and devouring their young; those of another species of the 

 same genus (P'. 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 (Myrmeleon) and Reaumur's improperly named 

 worm-lion (Leptis), whose singular stratagems will be detailed in a subse- 

 quent letter, both of which destroy numerous insects that are so unfortu- 

 nate as to fall into their toils. 



' The larvee of some species of Coccinellae feed, according to Prof. D. Reich, solely on 

 the leaves of plants ; as that of C. hieroglyphica, which eats the leaves of common heath 

 (Erica vulgaris) after the manner of the larvae of Lepidoptera. Der Geselhchaft naturf. Fr. 

 in Berlin Mag. ice. iii. 294. The larva of Coccinella Argus, Scriba (C. ii-maculata Fab.), 

 in like manner, Prof. Audouin found to feed on the leaves of the common Bryonia. (West- 

 wood, Mod. Classif. of Ins. i. 397.) * Macquart, Vipteres, i. 482. 



