( 284 ) 



Account of the Larva of a supposed (Eai'RUs Hominis, or 

 Gad-Fly, which deposites its Eggs in the Bodies of the Hu- 

 man Species ; with the particulars of a Case communicated 

 hy Dr Hill of Greenock. 



An accurate knowledge of the natural history of the genus 

 CEstrus (gad-fly or breeze), is of great importance in an econo- 

 mical point of view, when we consider that the most valuable of 

 our domestic animals, the horse, ox, and sheep, form the usual 

 nidus for their development and increase, and are frequently 

 incommoded, sometimes essentially injured, or even destroyed, 

 by their attacks. The insect called botts by farriers, is the larva 

 of the (Estrus Equi, and although Mr Bracy Clark (to whom 

 we owe the best account of that and other species of the ge- 

 nus *), concludes that, upon the whole, they are not injurious 

 to the horse, it appears from the accounts of Valisnieri, that the 

 epidemic which proved so fatal to the horses of the Mantuan 

 and Veronese territories during the year 1713, was primarily 

 occasioned by these larvae. The disease called staggers in 

 sheep is likewise occasioned by an insect of this genus ((Estrus 

 avis J, and the hides of cattle are perforated by another kind, 

 which hves beneath the skin. The reindeer of the Laplanders, 

 which has been said to unite in one animal the useful qualities 

 of many, is more than almost any other a martyr to a species of 

 gad-fly, probably peculiar to itself, and therefore named by na- 

 turalists (Estrus Tarandi. 



That man himself, the " Lord of the Creation," should be 

 the subject of similar attacks, is not so generally known. Hum- 

 boldt, however, mentions, that he examined several South Ame- 

 rican Indians, whose abdomens were covered with small tumors, 

 produced by what he inferred (for no very positive informa- 

 tion seems to have been acquired on the subject) to have been 

 the larvae of some species of CEstrus. Larvae of analogous forms 

 have also been detected in the frontal and maxillary sinuses of 

 Europeans ; and the surgical and physiological journals of our 

 own and other countries, have reported extraordinary instances 



• 3(1 Vol. of Linn. Trans. 



