256 INDIRECT BENEFITS DERIVED FROM INSECTS. 



lunaris, Geotrupes stercorarius and many other lamelli- 

 corn beetles, make large cylindrical holes, often of great 

 depth, under the heap, and there deposit their eggs sur- 

 rounded by a mass of dung in which they have previous- 

 ly enveloped them ; thus not only dispersing the dung, 

 but actually burying it at the roots of the adjoining 

 plants, and by these means contributing considerably to 

 the fertility of our pastures, supplying the constant 

 waste by an annual conveyance of fresh dung laid at 

 the very root ; by these canals, also, affording a conve- 

 nient passage for a portion of it when dissolved to be 

 carried thither by the rain. 



The coleopterous insects found in dung inhabit it in 

 their perfect as well as imperfect states : but this is not 

 the case with those of the order Diptera, whose Iarva3 

 alone find their nutriment in it ; the imago, which would 

 be suffocated did it attempt to burrow into a material so 

 soft, only laying its eggs in the mass. These also are 

 more select in their choice than the Coleoptera not in- 

 deed as to delicacy, but they do not indiscriminately 

 oviposit in all kinds, some preferring horse- dung, others 

 swine's-dung, others cow-dung, which seems the most 

 favourite pabulum of all the dung-loving insects, and 

 others that of birds. The most disgusting of all is the 

 rat- tailed larva that inhabits our privies, which changes 

 to a fly (Eristalis tenax] somewhat resembling a bee. 



Still more would our olfactory nerves be offended, and 

 our health liable to fatal injuries, if the wisdom and good- 

 ness of Providence had not provided for the removal of 

 another nuisance from our globe the dead carcases of 

 animals. When these begin to grow putrid, every one 

 knows what dreadful miasmata exhale from them, and 



