ERIOPHYID/E OR GALL-MITES. 



21 



easily recognised. In the former the buds are comparatively 

 small and pointed, whereas the latter are swollen and rounded. 

 A longitudinal section made in winter or spring through the centre 

 of both classes of buds will show a difference of structure. In the 

 case of the healthy buds — as, for ex- 

 ample, in the currant-bud mite — the 

 embryo leaves can be seen, and they 

 are always do^e at the apex, while in 

 the diseased buds the structural fold- 

 ings of the leaf are broken up, and 

 the apex always open. The same de- 

 scription holds good in forest trees in- 

 fested by Eriophyidaj. 



The life - history and microscopical 

 characteristics of the genus Eriophyes 

 form a most interesting study. It 

 belongs to the sub-family Eriophyidse 

 (Phytoptidae), — gall-mites of the order 

 Acarina. 



The mite is of a light yellowish 

 colour, and varies very much in size 

 according to species. Perhaps the size 

 of the creature may be approximately 

 put down as the ^r^^ ^^ toVo ^^ ^^^ 

 inch in length, and it is obviously 

 indistinguishable by the naked eye. 

 Fig. 22 may be regarded as a typical 

 mite. 



The body is of a vermiform shape, 

 and, like mites in general, is of one 

 piece, and with few appendages. Hence 

 a creature of such simple structure 

 atfords but few points for specific diflPer- 

 ences ; nevertheless, Nalepa gives a full 

 mite, together with a detailed 

 species.^ 



The form of the body is an elongated ellipse, narrowing towards the 

 posterior end ; and the cephalo-thorax is about the same breadth as 

 ^ Das Tierreich, 4 Lieferung (Eriophyida;). 1898. 



Fig. 22.— Phytoptus calycophthirns, 

 N(d. (Eriophyes rudis, Cancst.) 

 (Photo^iraphed from Nalepa's 'Gen- 

 era und Species derFamilie Phytop- 

 tida.' Wien, 1891.) 



description of a typical 

 description of the respective 



