224 INDIRECT BENEFITS DERIVED FROM INSECTS. 



(many species of SyrphidcB), whose grubs are armed with a 

 singular mandible^ furnished like a trident with three points, 

 with which they transfix their prey. They may often be 

 seen laid at their ease under a leaf or upon a twig, environed 

 by such hosts of Aphides, that they can devour hundreds 

 without changing their station ; and their silly helpless prey, 

 who are provided with no 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 trans- 

 fixes 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 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 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 favourite of our 

 childhood, which, as well as most of its congeners, in the 

 larva state, feeds entirely on Aphides^ ; 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 



^ The larvae 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 Gesellschaft naturf. Fr. in Berlin Mag. &c. iii. 294. The larva of Coccinella 

 Argus, Scriba(C W-maculata Fab.), in like manner, Prof. Audouin found to 

 feed on the leaves of the common Bryonia. (Westwood, Mod. Classif. of Ins. 

 i. 397.) 



