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XXI. On the Means of Destroying the Red Spider in the Melon 

 Frame. By Thomas Andrew Knight, Esq. F. R. S. Pre- 

 sidenL 



Read May 3, 1836. 



The Red Spider is one of the most formidable enemies with which 

 the gardener has to contend, and against which he is least well 

 prepared with the means of defence. His peach and nectarine 

 trees upon the open wall are often considerably injured by it ; 

 and the conservatory, the forcing-frame, and the stove, scarcely pre- 

 sent a plant which is not subject to suffer from its attacks. When 

 it appears upon trees growing upon walls in the open air, and 

 wherever water can be abundantly applied without material injury 

 to the plants, it is easily destroyed ; but there are, I believe, com- 

 paratively few plants, which are not much injured by having the 

 lower surfaces of the leaves much wetted. In a former Communi- 

 cation I stated the destructive effects upon the melon plant of the 

 application of water to the under surfaces of the leaves, apparently 

 owing to the cells of that surface of the leaf having absorbed the 

 lighter fluid, in the manner pointed out by M. Dutrochet, and 

 transmitted into the denser fluid, the vital sap of the plant. 



The aversion of the Red Spider to sulphur, or its inability to 

 live in the close vicinity of that substance, has long been known to 

 gardeners ; and the object of this Communication is only to point 

 out a more efficient mode of employing it than has, I believe, 

 hitherto been practised. The instrument which I use bears a very 

 close resemblance to those employed in fumigating with tobacco, 

 but it is filled with pieces of the wing feathers of pigeons or 

 poultry, amongst which a small quantity of flowers of sulphur is 



