SOCIETY OF CENTKAL ILLINOIS. 265 



arbor vita* and another on soft ina]>le in this country, hut never in 

 such numbers as to affect the hoaltli of the trees/' 



IN.TURIES BY GALL MITES. 



Mites of this »)[i-ou]) occur on perhajis the most of our fruit and 

 shade trees. They do not, like the sinuiiing mites, live exposed on 

 the leaves, but produce ^alls. p;rowths of hair, deformation of buds, 

 sten)s and leaves, and may, when favored by the conditions of moist- 

 ure and tem))erature, do <i:reat injurv by checkingr the orrowth or pre- 

 venting the formation of leaves. The currant, apple, vine, elm, lin- 

 den, maple and arbor vita^ have each a peculiar growth or deforma- 

 tion of their leaves produced by the work of gall mites. 



Owing to the feeble power of migration possessed by these mites, 

 they are not to be dreaded so much as the spinning mites. But they 

 are so small as to escape entirely the careless looker and are to be 

 feared on that account. In Europe they seem to be even more des- 

 tructive than in this country. The vine, according to Landois, is 

 damaged by them only less severely than by the parasitic fungus 

 Oidiiini tucl'eri. which there sometimes devastates vineyards. This, 

 or a related affection, occurs on American vines. On the ir)tli of 

 May, 1884, Prof. Forbes found in a vineyard, near Normal, Illinois, 

 two vines that were badly injured. Of the disease he says: "The 

 injury presents the form of peculiar warty elevations upon the upper 

 surface of the leaf, and corresponding depressions on the under sur- 

 face, these varying in size from one-twentieth to one-tenth of an inch 

 in diameter, although adjacent patches are frequently fused into 

 patches of much greater size. The larger vines of the leaf did not 

 share in this deformity, and the effect was a distortion, such as might 

 result from a shortening of these veins, and the consequent folding 

 and crumpling of the leaf." These growths, we are told, are not 

 exactly like those described l)y European writers, but this may be a 

 difference due to the way the plant responds to the attacks of the 

 raite. 



To Mr. Townend Glover, formerly Entomologist to the United 

 States Agricultural Dejtartment. is due the credit of having first 

 called attention in this country to a Phytoptus injury on the ])ear, 

 that seems to be gradually s])reading and increasing. It seems to be 

 identical with what has long been known to European fruit growers 

 and entomologists. It is produced by P}ii/fopfN.<^ pi/ri and consists on 

 young leaves of reddish swollen patches of tissue with openings on 

 the under side of the leaf. Upon older leaves the patches become 

 darker and are finally black. The mites live in the interior of these 

 galls in great numbers. 



Many other cases of injury could be given and described, but 

 these will suffice to give an idea of the nature of the injuries, which 

 is my only present purpose. When you find growths such as those 



