HARDWICKE'S SCI EN C E-GO SSIP. 



33 



The occupation of tlu; ricsh-flyis more legitimate 

 than that of those just named, and the insect seems 

 lo be but fuUilling its proper mission when it oc- 

 casionally assumes tlie role of the parasite. It is 

 true, its feeding-ground is more generally tlie dead 

 than the living subject ; still it is not averse, when 

 the occasion offers, to ciioose man as the nidus 

 on which to deposit its eggs or larvae (for several 

 species are vivipaious), and to rear its young. In 



Fiff. 23. Grub of 

 Myiwdtfrnia. 



Fi(j. 29. FlesVi-fly [S irco/ihaga 

 cuniuriii). 



this way it has often caused serious annoyance and 

 evendauger to life, laying its eggs in hot weather 

 on wounds and sores, where they speedily hatch, 

 and the grubs, instead of dropping to the ground, 

 eat their way into the flesh. A terrible story is 

 given by Kiiby and Spence (Introduction vol. i. 

 p. 137, ed. 4), of a beggar being almost literally 

 devoured alive by the larva of Hies, attracted by 

 some meat placed by the wretched man " betwixt 

 his shirt and skin." 



Fig. 30. Blow-fly {^Cadijihora fulmharbU). 



A similar story of a not less painful nature is re- 

 corded by M. Aristide Ptoger, in his "Lcs Monstres 

 invisibles " (p. 55). It has reference to the death 

 of a chiffonier, who was found a few years ago in a 

 ditch just outside Paris, still living, but with his 

 features completely destroyed by the multitude of 

 blow-fly grubs feeding on him. 



Man's perverse ingenuity has converted this 

 propensity of flies to devour living flesh into an in- 

 strument of torture ; for Plutarch assures us, that 

 in Persia state criminals were sometimes thus 

 punished. Por this purpose the wretched individual 



was fixed securely between two boats, the upper 

 being inverted over the lower, with only the feet, 

 hands, aud face exposed ; the latter being besides 

 smeared with honey. The result may be imagined. 

 Countless swarms of scav-enger flies, attracted by 

 their prey, deposited masses of eggs on the victim , 

 who was thus eaten alive. Persons have been 

 known to live for several days before they suc- 

 cumbed to this liorrible torture. 



Fig:. 31. Lucila honiinioorajt. Fig. 32. Grub of ditto. 



The principal parasites, at least in this country, 

 arethe different kinds of Tlesh-fly {Sarcophaga,^\g.'2^) 

 and Blow-fly or Blue-bottle {Calliphora, fig. 30), the 

 prolific parent of the " gentles," dear to the heart 

 of youthful Izaak Waltons. Prolific indeed they are ! 

 Degeer calculated that a single flesh-fly may deposit 

 about fifty larvse (for she is viviparous), and in the 

 course of six months may become the happy 

 mother of more than five hundred million descend- 

 ants! (Leunis, " Naturgeschichte des Thierreichs," 

 s. G20.) 



In addition to the above there are two flies, 

 whose habits have not been thoroughly studied ; 

 but the effect of whose parasitism is, in one case at 

 least, very serious. They are confined to the warmer 

 regions of America, and are known to the natives 

 under various names : in Brazil they are the Ura ; 

 in Costa Rica, the Torcel ; in New Granada, the 

 Gusano peludo; in Cayenne, the Ver macaque. 

 With regard to one of these flies. Bates speaks as 

 follows :— " A species of (Estrus or gadfly, on the 

 Upper Amazons, fixes on the flesh of man as a 

 breeding-place for its grub. I extracted five at 

 different times from my own flesh. The first was 

 fixed in the calf of my leg, causing there a sup- 

 purating tumour, which (being unaware of the 

 existence of this (Estrus) I thought at first was a 

 common boil. The tumour grew, and the pain in- 

 creased until I became quite lame, and then, on 

 carefully examining the supposed boil, I saw the 

 head of a grub moving in a small liole at its apex. 

 The extraction of the animal was a difficult opera- 

 tion, it being an inch in length and of increasing 

 breadth from head to tail, besides being secured to 

 the flesh of the inside of the tumour by two horn 



