ACARTNA OK MITES. 



121 



females liibernate during the winter months, seeking shelter in 

 such places as the cracks in hop-poles, under dead leaves, in 

 soil, in all crevices and shelters vs'here they are protected from 

 frost and snow. These, and all mites, flourish best in hot and 

 dry weather. They damage the plant in a twofold manner, — 

 first by sucking out the sap, and secondly by blocking up the 

 stomata of the plant by their webbing and excreta. The 

 mouth consists of a pair of biting jaws and- a sucking-tube be- 



Fn;. 51. — Red Spider {Tetranychiis nuilvw). 

 A, Eg;^^s on leaf ; B, larva ; c, foot of mite ; d, adult. 



tween. The tissue is first bitten, and then the sucking-tube is 

 thrust into the hole and the sap extracted. No mites, we must 

 remember, have any external breathing-pores, but respire by 

 the whole body-surface. All washes used for destroying them 

 should contain sulphur or paraffin, as they are the most powerful 

 acaricides. Liver of sulphur is found to be the best form of 

 sulphur to use for these pests. The Eed Spider of the vine 

 (T. telarius) works in a similar way. It is best kept down by 

 repeated sprayings of cold water. 



The genus Bryohia, which belongs to the Trombididse, has 

 several species destructive to fruit-trees. These fruit pests can 

 be told from Tetranychus by having the first pair of legs long, 

 whereas in Tetranychus they are all the same length. They 

 spin no webbing. Mature Bryobia are about ^^y- of an inch 



