VORACITY OF MAGGOTS. 



271 



elevates into the air, that he may not be disturbed with 

 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 aphidivor- 

 ous flies, surrounded with heaps of the skins of the 

 slain, the trophies of their successful warfare.'* 



The larvae of the lace-winged flies (Hemerobidce, 

 LEACH) are even more destructive to the aphides than 

 either of the preceding; insomuch that Reaumur was 

 induced to call them the lions of the aphides. The 

 mandibles of the larva of Hemerobius are somewhat 

 crescent-shaped, and, like those of the ant-lion, are 

 hollow, by means of which they suck the juices of 

 their victims. These are rarely so numerous as the 

 two preceding families, but they make up for their 

 fewness in the voracity with which they devour the 

 little destroyers of our vegetables. 



* Intr. i, 264. 



a, Lace-winged fly ; 5, the grub of the same, magnified ; c, 

 syrphus ; rf, larva of the same devouring the aphides of the eld- 

 er ; , the head magnified, to show the mouth. 



