432 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol, 3 



During the time that the mites are feeding on the foliage of trees, 

 they are green in color, with dark colored spots plainly showing on the 

 dorsum. As soon as feeding ceases the color almost immediately 

 changes to some shade of orange, or red. The first mites found 

 migrating to the ground this season, were a light orange color, with 

 one large dark spot in the center of the dorsal surface of the body. 

 When kept in a small box for a few days these gradually became 

 more red in color, and all trace of the dark spots disappeared. The 

 dark spots are undoubtedly due to the body contents of the mites, 

 and the red color seems to be an indication that feeding has ceased. 

 This is true at least, for the mites that feed upon orchard trees. 



Control of T. bimaculatus. — Occasionally it becomes necessary to 

 fight this pest by means of a spray, and we have found nothing better 

 than sulphur, which may be either dusted on the trees, or applied with 

 water as a liquid spray. I have had splendid success in treating trees 

 for this red spider, with one pound of sulphur in from three to five 

 gallons of water, the weaker mixture being apparently just as effective 

 as the stronger. A small amount of soap used in the water, will cause 

 the sulphur to settle to the bottom of the spray barrel or tank, and a 

 good agitator will keep it stirred up in fairly good shape, so that a 

 thorough application may be made with any of the ordinary nozzles. 

 It is important that the sulphur be finely screened so that all lumps 

 may be taken out before using. Lime and sulphur applied in the 

 early spring while the trees are dormant, has not proven a successful 

 spray for T. bimaculatus. A great many orchards treated with lime 

 and sulphur in the spring, have been observed this summer, and 

 while Bryobia pratensis has been practically exterminated in all 

 orchards where such a spray was used, Tetranychus bimaculatus has 

 later appeared abundantly. 



The tiny black lady-bird beetle, Scymnus punctum, is quite com- 

 monly found feeding on red spiders, but nowhere has it been found 

 plentiful enough to be of much service in their control. 



Wintering of Bryobia pratensis. — This species of mite is com- 

 monly found in the egg stage during the winter season. Occasionally, 

 however, they have been found in houses where the adults hibernate, 

 causing more or less inconvenience to the house-wife. Their tiny red 

 eggs are very commonly found on almond, pear, plum, prune, cherry, 

 apple and peach trees. 



Summer habits of B. pratensis. — The injury to trees from B. 

 pratensis is quite similar to the injury from T. bimaculatus. The 

 absence of webs often makes it more difficult to detect this species. 

 The same varieties of trees were found infested with the brown mite 

 that were found infested with the red spider. There seems to be a 



