152 INDIRECT BENEFITS DERIVED FROM INSECTS. 



means of defence, so far from thinking of escaping, frequently walk over 

 the back of their enemy, and put themselves in his way. When disposed 

 to feed, he fixes himself by his tail, and, being blind, gropes about on 

 every side, as the Cyclops did for Ulysses and his companions, till he 

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

 into the air, that he may not be disturbed by its struggles, and soon de- 

 vours. The havoc which these grubs make amongst the Aphides is asto- 

 nishing. It was but last week that I 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 larvas of aphidivorous flies, 

 surrounded with heaps of the skins of the slain, the trophies of their suc- 

 cessful 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 favourite of our childhood, which, as well as 

 most of its congeners, in the larva state, feeds entirely on Aphides l ; 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 igno- 

 rant that their little visitors 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 Fly, so fre- 

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

 countries the children have taken these friendly Coccinellas under their 

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

 them Vaches a Dieu, Betes de la Fierge, &c. ; and with us, commisera- 

 tion 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 larvas of Coccinellas or of 

 aphidivorous flies collected from less valuable vegetables. 



Lastly, to close this list of imparasitic insectivorous larvas, 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 (V. zonaria Meig.), which MM. de St. Fargeau and Serville 

 have ascertained to live in wasps' nests and destroy great numbers of their 



* The larvae of some species of Coccinellas 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 larvaa of Lepidoptera. Der Gesell- 

 schaft naturf. Fr. in Berlin Mag. &c. iii. 294. The larva of Coccinella Argus, Scriba 

 ((7. \\-maculata Fab.), in like manner, Prof. Audouin found to feed on the leaves of 

 the common Bryonia. (Westwood, Mod. Class, of Ins. i. 397.) 



