Insects, etc., Injurious to the Gooseberry. 279 



which govern the rapid increase of this acarus are not known. It is 

 generally said that heat and drought are responsible, but when one 

 goes over a number of statistics and meteorological records this does 

 not appear to be the case. The mites certainly feed more and are 

 more noticeable in warm sunny dry weather, and the bushes are not 

 so hardy, but there does not seem to be any excessive reproduction 

 from those causes. 



Some of the worst attacks I remember have been after warm 

 damp weather. The Eed Spider is, of course, not an insect, it 

 belongs to the eight-legged group of "jointed limbed animals," and 

 to that section called Acarina. 



The young of these Eed Spiders are very like the adult, but have 

 only six legs, as we find in the insects. They are oviparous, and 

 the eggs (Fig. 192) are small globular bodies, very similar to those 

 of the Hop Eed Spider (Tctranyclius malvce); but on their smooth 

 shell are a few white fibres. 



The damage done by the mites is by their constantly sucking the 

 sap from the leaves. The appearance produced is very marked, the 

 larger leaves become marbled grey, sometimes almost silvery ; the 

 young leaves are stunted in bad attacks and present the appearance 

 shown in the photograph reproduced here. The result is that the 

 leaves and blossoms and even young fruitlets fall off. 



This pest is well known in Cambridgeshire, Worcestershire, Devon, 

 Cornwall, Gloucestershire, Kent, Surrey, Sussex, Middlesex, and 

 extends up into Scotland. We may say practically wherever goose- 

 berries are grown the Eed Spider is found. 



It has been described in various ways, some calling it Tctranychus 

 tdarius, one of the web spinning mites, others stating it is the same 

 as the Eed Spider on ivy, and calling it Bryobia pretiosa (2). 

 Ormerod, quoting Harker, refers to this mite forming silken webbing 

 " covering the whole of the ivy for quite one or two hundred yards," etc. 



If this is the same species as she refers to on ivy in other places, 

 it has nothing to do with the Eed Spider of the gooseberry, for it 

 does not form a web. Although Michael says (2) that it " swarms in 

 millions on the ivy in gardens," we venture to doubt, under the 

 circumstances, that they are the same acarus. The mite on ivy does 

 not agree with the common gooseberry pest, which is apparently 

 Bryobia nobilis, the same as the Bryobia ribix, Thomas.* 



* A recent examination made of the ivy Bryobia (B. pretiosa} shows 

 hairs of broad white structure in all stages of the mite. The Red Spider 

 of gooseberries has only simple hairs in all its stages, so that the two can be 

 easily separated. 



