124 Bulletin Wisconsin Natural History Society. [Vol. 7, Nos. 3-4. 



seldom dark brown when they are greatly shrivelled, hardened 

 and distorted, — with which my observations agree. The young 

 gall has a smooth interior, but fills with granular or smoothly 

 bulging excrescences until, with the shrivelling of the old gall, the. 

 cavity is nearly filled. There may be from one to over a hundred 

 galls per leaf, but I unfortunately did not see several hundred as 

 reported by Banks (1905), Garman (1882), or several thousand 

 as stated by Shinier (1869). 



The best redescription of the mite is given by Parrott (1908), 

 with which my microscopic examination agrees except that I had 

 only September-October material to examine. Parrott here 

 changes the generic name to Phyllocoptes and enters into their 

 life history. 



As is so usual with gall insects, I noticed a very wide differ- 

 ence in gall distribution on the trees. One or two healthy trees 

 near the Chicago & Northwestern R. R. track were almost free 

 from galls, as I found but one or two leaves with a gall or two 

 apiece. Others, especially the smaller trees, were infested from 

 top to bottom of the crown, a few small leaves being so thoroughly 

 covered as to be crumpled all out of shape. As these trees prob- 

 ably represent only two separate plantings when Day Avenue was 

 first laid out, the smaller trees of each planting undoubtedly repre- 

 sent the less thrifty, perhaps unhealthy specimens, these being 

 worst affected with galls. Again, of two trees of equal and 

 thrifty proportions, one would have a few branches, usually the 

 lower, slightly infested with a few galls on some leaves, and the 

 other have a whole branch or all the lower branches, especially 

 on the sunny side of the tree, thoroughly infested with one to 

 mostly many galls per leaf, and seldom a leaf on the whole branch 

 uninfested. On the better trees, no shrivelling or dwarfing of 

 the leaf appears ; so that the chief disfigurement of the tree seems 

 to be the dirty variegated speckling of the leaves by the galls. 



HABITS VS. REMEDIAL MEASURES. 



Parrott (1908) says that the winter quarters of this common 

 and widely distributed species "seems not to have been deter- 

 mined. While occasionally a specimen may be found in hiding 

 under a bud scale, the buds generally harbor only a very few, 

 which represents but an exceedingly small fraction of the mites 

 that have been produced for that season on the tree." I examined 



