INDIRECT BENEFITS DERIVED FROM INSECTS. 147 



called in America the Tumbledung, whose singular manoeuvres I shall 

 subsequently have to advert to, Copris lunaris, Geotrupes stercorarins, and 

 many other lamellicorn beetles, make large cylindrical holes, often of 

 great depth under the heap, and there deposit their eggs surrounded by a 

 mass of dung in which they have previously enveloped them ; thus not 

 only dispersing the dung, but actually burying it at the roots of the ad- 

 joining 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 con- 

 venient 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 larvae 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 indeed 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. 1 The most disgusting of all is 

 the rat-tailed larva that inhabits our privies, which changes to a fly (Eiis- 

 talis tenax), somewhat resembling a bee. 



Still more would our olfactory nerves be offended, and our health liable 

 to fatal injuries, if the wisdom and goodness of Providence had not pro- 

 vided for the removal of another nuisance from our globe the dead 

 carcasses of animals. When these begin to grow putrid, every one knows 

 what dreadful miasmata exhale from them, and taint the air we breathe. 

 But no sooner does life depart from the body of any creature, at least of 

 any which from its size is likely to become a nuisance, than myriads of 

 different sorts of insects attack it, and in various ways. First come the 

 Histers, and pierce the skin. Next follow the flesh-flies, some, that no 

 time may be lost (as Sarcophaga carnaria, &c.), depositing upon it their 

 young already hatched ; others (Musca Ccesar, &c.), covering it with 

 millions of eggs, whence in a day or two proceed innumerable devourers. 

 An idea of the dispatch made by these gourmands may be gained from the 

 combined consideration of their numbers, voracity, and rapid development. 

 One female of S. carnaria will give birth to 20,000 young ; and the larvas 

 of many flesh-flies, as Redi ascertained, will in twenty-four hours devour 

 so much food, and grow so quickly, as to increase their weight two 

 hundredfold ! In five days after being hatched, they arrive at their full 

 growth and size, which is a remarkable instance of the care of Providence 



1 According to M. Robineau Desvoidy, the dung of the badger, which is placed in 

 a separate chamber of its subterranean galleries, has its peculiar fly, which he names 

 Leria melina, the larvae of which there feed upon it; and the parent flies never 

 ascend to the surface, but constantly reside in this dark and damp abode, and can 

 only be obtained by digging into it. Another fly, his Thelida vespertilionea, in like 

 manner, lives in the larva state on the dung of bats deposited by them at the end of 

 the grottoes of D'Arcy-sur-Eure more than one hundred toises distant from their 

 entrance ; and he describes a third fly, Leria mustelina, -which he believes to feed on 

 the dung of the weasel, and names other distinct species to which the dung of the 

 fox, the rabbit, the water-rat, and the field-mouse respectively afford subsistence. 

 (Ann. Soc. Ent. de France, x. 255260.) 



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