Forest entomology . this species in several parts of Northumberland. Eriophyes psilaspis (JSTal.)Phytoptus taxi (Murray). This species (fig. 25) was first discovered by Professor Sir ThiseltonDyer in the spring of 1875 doing immense damage to young hedges, which damage had hither-\£*- to been ascribed to frost. I found it plentiful onthe under side of thelower branches of ayew-tree at High Legh,Cheshire, from which thephotographic illustrationwas taken. I have oftenfound it very injurious toyoung yew-trees in thenursery - lines, and alsooccasionally on yewhedges. As this species is cer-
Forest entomology . this species in several parts of Northumberland. Eriophyes psilaspis (JSTal.)Phytoptus taxi (Murray). This species (fig. 25) was first discovered by Professor Sir ThiseltonDyer in the spring of 1875 doing immense damage to young hedges, which damage had hither-\£*- to been ascribed to frost. I found it plentiful onthe under side of thelower branches of ayew-tree at High Legh,Cheshire, from which thephotographic illustrationwas taken. I have oftenfound it very injurious toyoung yew-trees in thenursery - lines, and alsooccasionally on yewhedges. As this species is cer-tainly injurious, it iswell to have recourse tosome remedial the case of hedges,where regular trimmingis resorted to, it would be well to burn all primings; and as regardsthe young yew-trees in nursery-lines, it would be best to hand-pick theinfested buds, say about the latter end of May, and burn them. 1 Tubeuf, Diseases of Plants induced by Cryptogamic Parasites. Englishedition, by W. G. Smith. -Abort!re swollen buds caused by Eriophyespsilaspis on English yeio. ERIOPHYJD^E OR GALL-MITES. 27 Species living in Galls. There are numerous species living in galls on the leaves of varioustrees, but the following are a few typical examples. They are nottrue galls, however, but simply pseudo-galls; and it is important tocompare the structure of the pseudo-galls of Eriophyinae with the truegalls of gall-forming insects. The former is simply an abnormal thick-ening of the leaf, with an opening or passage leading into the pseudo-gall. The opening is surrounded by hairs, which doubtless act as aprotection against the inroads of parasitic acari and other naturalenemies. The true gall, on the other hand, is always closed, and theform variable and immaterial. Some species of leaf-miners (Lepidop-tera) form conical galls or cases on the upper side of the leaf, but thepassage communicates between the epidermal skins, and has no open-ing through the under side of the leaf,
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