678 Agricultural Gazette of N.S.W. [Aug. 2, 1920. 



The Pf ar-leaf Blister Mite. (Eriophyes pyri, Pagenstecher). 



This is a well known cosmopolitan pest upon the foliage of the pear tree. 

 Hibernating in the bracts of the leaf buds, it attacks the tiny unfolding 

 leaves, causing them to develop variegated reddish-green blisters, which, 

 as the leaves mature, become brownish-black patches of thickened tissue 

 spread all over the leaf. Tn these the full-grown mites shelter ; they emerge 

 through a minute opening on the under-surface of the infes.ted leaf. The 

 adult mites are white, of the typical cylindrical form, with the two pairs of 

 short legs on the hind margin of the head. They are just noticeable to the 

 naked eye when moving out of the gall, and measure about -^^ of an inch. 



This mite was described from Germany in 1857, and it is common in 

 England. Miss Ormerod, in her account of this orchard pest (" Handbook 

 of Orchard and Bush Fruit Insects," p. 127), reproduces Nepaula's figui'e of 

 it, and states that she could always get specimens for study in her orchard. 

 It was probably introduced into the United States from Europe at a veiy 

 early date, as it was identified and described from that country in 1872. Dr. 

 James Fletcher states that it does a considerable amount of damage in 

 Canada. We have no early record of its introduction into Australia. Eraser 

 Crawford noted it in South Australia in 1881 ; French, in the first part of 

 his " Handbook of the Destructive Insects of Victoria," records it from that 

 State in 1891 ; and Dr. Cobb noticed it in this journal in the same year, 

 giving in the year following a woodcut and general account of it, and 

 pointing out that it might often be mistaken for pear-leaf scab (Fusicla- 

 dium fyrinum). As the treatment of these two leaf jDests is very different, 

 their identification is important. Dr. Cobb showed that they could be 

 distinguished from each other when examined through a low-power lens, the 

 mite galls being furnished with a small opening which the fungus galls lack. 



Experiments, carried out at Cornell University hy Professor Slingerland 

 show that the pear-leaf blister mite can be easily controlled b}' spraying 

 w^th kerosene emulsion, diluted with from five to seven parts of water, any 

 time after the leaves have fallen. At this time all the mites will have left 

 the dead and dying leaves, and will be wintering in the bracts of the leaf buds 

 before attacking the opening leaves in the coming spring. If the spraying 

 is carefully carried out, and every bud drenched, all the mites will be killed 

 by the oil. This mite is not uncommon at times in our pear orchards, 

 particularly in the soutliern districts, but is seldom plentiful enough to 

 defoliate the trees as it is said to do in other countries. 



The Vine-leaf Blister Mite {Eriophyes vitis, Landois). 

 A native of Europe, this mite was accidentally introduced into the United 

 States, and according to Essig is now found in all the vine-growing districts 

 of California. It probably came across the Pacific to this country, and is 

 certainly a recent introduction — probably of the last ten years. During the 

 last two, however, it has spread all through the vineyards of the county of 

 Cumberland ; many specimens of blistered leaves were forwarded to the 

 Department during the last summer. 



