FOOD OF INSECTS. 385 



the flesh of the insects hito which they have insinuated 

 themselves. Some of the CEstri, fixed in a spacious 

 apartment beneath the skin of an ox or deer, regale 

 themselves on a purulent secretion with which they are 

 surrounded. Others of the same tribe, partial to a higher 

 temperature, attach themselves to the interior of the sto- 

 mach of a horse, and in a bath of chyme of 102 degrees 

 of Fahrenheit revel on its juices. The various species 

 of horse-flies dart their sharp lancets into the veins of 

 quadrupeds, and satiate themselves in living streams; 

 while the gnat, the flea, the bug, and the louse, plunge 

 their proboscis even into those of us lords of the creation, 

 and banquet on "the ruddy drops which warm our 

 hearts." Some make their repast upon birds only, as 

 the fly of the swallow, and other Ornithomyia, and 

 the bird-louse ; insects nearly allied, though one is di- 

 pterous and the other apterous. And a most singular 

 animal belonging to the latter tribe {Nycteribia Vesper- 

 tilwnis) revenges upon the bat its ravages of the insect 

 world ^. Another numerous class kill their prey outright, 

 either devouring its solid parts, as the predaceous and 

 rove-beetles, &c., or imbibing its juices only, as the infinite 

 hordes of the field-bug tribe. And the larvae of the gnat, 

 chameleon [Stratyomis), and other flies aquatic in that 

 state, the leviathans of the world of animalcules, swallow 

 whole hosts of these minute inhabitants of pools and 

 ponds at a gulp, causing with their oral apparatus a 

 vortex in the water, down which myriads of victims are 

 incessantly hurried into their destructive maw. 



But not only animals themselves, almost every animal 

 substance that can be named is the appropriate food of 

 =" Linn. Trans, xi. 11. t. 3,/. 3—7. 



VOL. I. 2 C 



