78 First Report on Economic Zoology. 



lime trees. There are a number of species of Oribata ; one, 0. gldbata, 

 is often present in swarms on fruit trees, especially the plum. 

 Instead of finding them injurious, they appear to be either beneficial 

 or non-obnoxious. They have been seen feeding off the spores of the 

 canker fungus and various green vegetal matters on fruit trees. But 

 in one or two instances fruit-growers have noticed that they have 

 done some harm to the leaves. They often swarm in the forks of 

 the boughs and axils of the twigs and buds. The species sent by 

 Mr, Bii'knell has been identified by Albert Michael as Oribata 

 orbicularis, which also occiu's on various fruit trees in Kent. 



This species has been dealt with in the Journal of the South- 

 Eastern Agricultural College (No. 6, p. 11 (1897)). Albert Michael, the 

 chief authority on Mites, agrees that these Oribatidae do no practical 

 harm. Several fruit-growers have informed me that they cause the 

 leaves of the plum to die off, however. It is possible this may have 

 been due to other causes. All cases personally investigated have 

 shown no damage to the trees, although thousands of these shiny mites 

 were present. 



Treatment. 



Soft soap wash as suggested by a coiTespondent would be quite 

 useless. The Oribatidse have very hard chitinous skins, and probably 

 no wash that could be used in the summer would affect them. Late 

 in the autumn caustic alkali wash might be tried and might prove 

 beneficial. 



The method of preparing and using the alkali wash will be found 

 in Leaflet 70 of the Board of Agriculture. 



'O^ 



The Pear-Leaf Blister Mite. 



(Uriophycs ipyri, Sch.) 



Several enquiries were made concerning the Pear-Leaf Blister 

 Mite during 1902. Information was sent that these little acari 

 enter the leaf by the stomata and live in the soft internal tissues, 

 where they soon commence to form a galled patch. They move from 

 leaf to leaf, bvit spread very slowly. Often one tree in an orchai'd 

 will be attacked for years before any neighbouring ones show signs of 

 having contracted the disease. Frequently we see a single branch of 

 a tree diseased year after year and yet the rest of the tree remains 

 clean. In nearly all cases I have seen, the fruit becomes hard and 

 gritty and is usually deformed. All we can do is to hand-pick the 



