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



they have had a little time to get over their sluggishness, as found 

 in newly opened galls. Perhaps daylight awakens their migra- 

 tory speed. Lintner ( 1888) recommends burning infested leaves in 

 June, but in trees so badly infested, this would be more serious for 

 the tree than for the mites ; for the leaves seldom falling in June, 

 would have to be completely burned off many trees. This migra- 

 tion is peculiar, as the mites are quite generally in their galls in 

 October, unless this migration be of a distinct, earlier generation. 

 In that case, the final whereabouts of the July migration compli- 

 cates any remedial measure short of the expensive spraying for 

 that migration, as suggested by Parrott. Although I discovered 

 the mite infested region July 6, it was not until middle August 

 when I moved into the region and had a little time to study them, 

 so cannot say if there were a July migration here. 



NATURAL ENEMIES. 



As to natural enemies, Dr. Felt wrote me, Oct. u, "I fear 

 there are comparatively few records dealing with its natural ene- 

 mies." None are mentioned in the authors available to me. 



In August, I thought I saw a tiny worm within an opened 

 gall I was examining, violently jerking himself as if disturbed 

 by my intrusion. I carefully preserved this till I could show it 

 to C. T. Brues next day. He examined with his microscope 

 without finding anything. We opened about fifty fresh galls on 

 different occasions without result. In October, however, I found 

 two worms in galls on the same leaf. They had mite exuviae 

 sticking to them here and there on all parts, but no hostile attitude 

 towards living mites could be proved. They were of a light 

 almost transparent amber color with brownish central interior 

 mass about midway the length, and while shiny were slightly 

 papillate. On removal to a tiny vial with cotton plug, with fresh 

 galls cut open and living mites, they showed no ability to crawl, — 

 merely squirmed and dried up in a day. This probably happened 

 to the first specimen lost. Further evidence showed that although 

 in contact with the galls, they stuck to the glass and kept their 

 shape, though slightly contracted. 



Despite the gall has been described as smooth in the interior, 

 in most of the galls turned black and dry there was evidence of 

 loose trichomes, but in some, fungus filaments. In many of them, 

 living salmon-colored mites existed, but most had dead bodies 



