THE FLY- WEEVIL. 



292 



tight cafks or granaries, will be an effeaual prefervative of 

 the wheat from the injury of flics. It likewife proves, 

 what is very ufeful to be known, that fly-injured wheat 

 in the holds of large veflels, or in deep bulk in granaries, 

 will not receive further damage from infeds, but on thofc 

 furfaces which are expofed to the acceflion of frefla air. 



The following experiment on peafe, is. an encourage- 

 ment to attempt tlie prefervation of wheat, by excluding 

 air from it. Take any quantity of Englifli peafe intended 

 for feed, divide them into two parts, put one m an open 

 veflel, keep the other in a veffcl well corked; that parcel 

 to which the air has had admiflion, will be worm eaten in 

 the fpring, whilft the other remains fonndj and imtouch- 

 cd by iufeds. 



^ It would he a great point gained, to deftroy all thcfc 

 flies in granaries and mills, by poifon vapour, if it could 

 be eafily done.' But Mr. Duhamel {sljs no other vapour, 

 but that from burning fulphur, which is injurious to the 

 grain, will do it. This affertion is extraordinary, and the 

 truth of it is to be doubted, fince all other infeds are rea 



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dily killed by vapours of various kinds. " If bonc,^ of 

 animals, or hartfliorn, are laid on an open fire, in a roomi 

 where the fmoke is confined, it will kill all the bugs, fleas 

 and flies in that room: But the leaft naufeous, and yet the 

 moft deadly vapours, are from the fuffocation of fire: thus 



the fpirits of charcoal, confined in a clofe room, kills the 

 ftrongeft animals hi a fliort time;" and therefore it may 

 rationally be cxpcded, that a pot of thefe coals fired, in a 

 clofe granary, coukl not fail of dcflroying the flics in it in 

 one night: However, there is no determining this matter 

 a priori becailfc of the difference in refpiration between 

 animals and infeds; the former taking in air by the nof- 

 trils,^ and the latter by a perforation in the abdomen. 

 But if the fumes of burning charcoal be inofFenfivc to the 

 flies, it is probable that filling the room with a thick, pun- 

 gent, oleaginous fmoke, fiich as arifes from burnin*-*- the 

 jflems of tobacco, would foon deflroy them, by clogging 



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