74 



4. Xo suggestions are made for the control of the Black 

 Currant- Mite on other host plants. The attacks either appear 

 to be rare or, more probably, are overlooked. 



RED SPIDERS. 



BED SPIDER (greatly magnified). 



The pests so well known to horticulturists as " Red 

 Spiders " are in reality mites and belong to the group which 

 includes the Cheese Mites, Gall Mites, and similar pests. 

 They comprise a number of different kinds, all very much alike 

 but fortunately the precise differences between them are not 

 of vital importance from the practical point of view. It will 

 therefore be sufficient to note that there are two sections of 

 which one, characterised by the Gooseberry Red Spider 

 (Bryobia), spins little or no web, while the other, of which the 

 Greenhouse Red Spider (Tetranychus) is typical, usually spins 

 a fairly thick silken web. Naturally the kinds which make a 

 thick web are more difficult to kill by spraying than those 

 not so protected and the difference is therefore worth observing. 



Plants Attacked and Nature of Damage. The injury to 



^onsob'MTies and hops arid to plants under glass such as vines or 

 cucumbers, is perhaps of most importance, but Red Spiders 

 are also found on most fruit trees, many flowering plants 

 (e.g., violets), and a number of trees and shrubs such as 

 the lime, gorse and ivy. 



The injury in all cases is done by the feeding of the Red 

 Spiders, both young and old, which bite into the leaf, usually 



