436 Insect Architecture. 



grubs ; but there is every appearance that they do not at all 

 afflict, or only afflict it with little pain. For this reason 

 cattle most covered with bumps are not considered by the 

 farmer as injured by the presence of the fly, which generally 

 selects those in the best condition. 



A fly, evidently of the same family with the preceding, 

 is described in Bruce's ' Travels,' under the name of zimb, as 

 burrowing during its grub state in the hides of the elephant, 

 the rhinoceros, the camel, and cattle. " It resembles." he 

 says, " the gad-fly in England, its motion being more sudden 

 and rapid than that of a bee. There is something peculiar 

 in the sound or buzzing of this insect ; it is a jarring noise 

 together with a humming, which as soon as it is heard all the 

 cattle forsake their food and run wildly about the plain till 

 they die, worn out with fatigue, fright, and hunger. I have 

 found," he adds, " some of these tubercles upon almost every 

 elephant and rhinoceros that I have seen, and attribute 

 them to this cause. When the camel is attacked by this fly, 

 his body, head, and legs break out into large bosses, which 

 swell, break, and putrefy, to the certain destruction of the 

 creature."* That camels die under such symptoms, we do 

 not doubt; but we should not, without more minutely- 

 accurate observation, trace all this to the breeze-fly. 



MM. Humboldt and Bonpland discovered, in South Ame- 

 rica, a species, probably of the same genus, which attacks 

 man himself. The perfect insect is about the size of our 

 common house-fly (Musca domestica), and the bump formed 

 by the grub, which is usually on the belly, is similar to that 

 caused by the ox breeze-fly. It requires six months to come 

 to maturity ; and if it is irritated it eats deeper into the flesh, 

 sometimes causing fatal inflammations. 



GRUB PARASITE IN THE SNAIL. 



During the summer of 1829, we discovered in the hole of a 

 garden-post, at Blackheath, one of the larger grey snail shells 

 (Helix aspersa, MULLER), with three white soft-bodied grubs 

 * Bruca's Travels, i. 5, and v. 191. 



