DIRECT INJURIES CAUSED BY INSECTS. 69 



Our friend Captain Green, of the sixth regiment of the East India Com- 

 pany's native troops, relates to me, that in India, when the mangoes are ripe, 

 which is the hottest part of the summer, a very minute black fly makes its 

 appearance, which, because it flies in swarms into the eyes, is very 

 troublesome, and causes much pain, is called there the eye-fly. At this 

 season the eyes are attacked by a disease, supposed to be occasioned by 

 eating the mangoes, but more probably the result of the irritation produced 

 by the fly in question, which, however, they admit carries the infection 

 from one person to another. 



You know that the hairs taken from the pods of Dollchos pruriens and 

 urens L., commonly called Cowhage and Cow-itch 1 , occasion a most violent 

 itching, but perhaps are not aware that those of the caterpillars of several 

 moths will produce the same disagreeable effect. One of these is the pro- 

 cession-moth (Cnethocampa processionea), of which Reaumur has given so 

 interesting an account. In consequence of their short stiff hairs sticking 

 in his skin, after handling them, he suffered extremely for several days ; 

 and being ignorant at first of the cause of the itching, and rubbing his eyes 

 with his hands, he brought on a swelling of the eyelids, so that he could 

 scarcely open them. Ladies were affected even by going too near the nest 

 of the animal, and found their necks full of troublesome tumours, occa- 



found that by extending over the outside of his windows nets of a very fine pack- 

 thread with meshes 1^ inch to the square, so fine and comparatively invisible that 

 there was no apparent diminution either of light or the distant view, he was enabled 

 for the remainder of the summer and autumn to enjoy the fresh air with open win- 

 dows without the annoyance he had previously experienced from the intrusion of 

 flies, often so troublesome that he was obliged on the hottest days to forego the 

 luxury of admitting the air by even partially raising the sashes. " But no sooner 

 (he observes) had I set my nets than I was relieved from my disagreeable visitors. 

 I could perceive and hear them hovering on the other side of my barriers; but 

 though they now and then settled on the meshes, I do not recollect a single instance 

 of one venturing to cross the boundary." 



It is singular, too, as was first pointed out by Mr. W. B. Spence (Ent. Trans. L 

 7.) that Herodotus 2200 years ago stated that the Egyptian fishermen protected 

 themselves in a similar manner from the attacks of mosquitos by spreading their 

 fishing-nets over their beds ; a fact which has greatly puzzled all his commentators, 

 who, not conceiving the possibility of mosquitos being kept off by fishing-nets, which 

 must necessarily have wide meshes, have supposed the father of history to have 

 alluded to some protection of fine linen similar to the gauze nets now used against 

 these insects. But in this, as in so many other instances, the supposed error is not 

 that of Herodotus, but of his commentators, who, ignorant of the fact above related 

 as to flies being excluded by wide- meshed nets, could not conceive of it in the case 

 of mosquitos ; yet, in confirmation of its accuracy, I have been told by a friend that 

 he was assured by a gentleman, who had travelled in America, that he had often 

 had mosquito nets with meshes an inch square put over his bed, and had found them 

 a perfect security from their bites, though, as is well known, they will creep through 

 any small hole in an ordinary gauze net. 



In concluding this long note it may be observed that the number of house flies 

 might be greatly lessened in large towns, if the stable dung, in which their larvaa are 

 chiefly supposed to feed, were kept in pits closed by trap doors, so that the females 

 could not deposit their eggs in it. At Venice, where no horses are kept, it is said 

 there are no house flies ; a statement which I regret not having heard before being 

 there, that I might have inquired as to its truth. 



1 Cowhage has been administered with success as an anthelmintic, as has likewise 

 spun glass pounded ; the spicula of these substances destroying the worms. The 

 hair of the caterpillars here alluded to, and perhaps also of the larva of Euprepia 

 Caja (the Tiger-Moth), might probably be equally efficacious. 



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