88 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
RESULTS OF SPRAYING AND DUSTING FOR THE CONTROL 
OF THE RED SPIDER {PARATETRANYCHUS PILOSUS) 
By D. M. DeLong, Ass 7 Prof, of Entolomogy, Ohio State University 
Abstract 
Red spider, Paratetranychus pilosus, has been a serious pest on several types of 
fruit trees in the Erie-Chautauqua fruit section. The mites appear on the foliage 
early in the spring and develop from egg to adult in two to three weeks, there being 
such an overlapping that eggs and adults were always present; consequently effective 
dusts must remain active upon the foliage for some time. A lime sulphur wash, 1 
to 40 easily controls red spider, though it is too strong for prune foliage, which at 
times may be seriously injured by 1 to 75. The control by various sulphur dusts in 
combination with arsenate of lead or nicotine did not vary greatly, ranging from 50 
to 60 percent. Soap added to a lime sulphur wash, increases its value by at least 
5 to 10 percent. A 1 percent lime sulphur with 6 lbs. of sulphur paste for each 100 
gals, and 1 lb. of resin fish oil soap gave very satisfactory control. 
For several years the red spider (.Paratetranychus pilosus) has been a 
very serious pest on the foliage of several types of fruit trees in the Erie 
Chautauqu? fruit section. Injury has been especially serious on the 
foliage of York State prunes, in many cases being so conspicuous that the 
yellowing of the foliage could be noticed at some distance from the orch¬ 
ard. As a consequence severe losses were suffered due to the delayed 
ripening, sour flavor and smaller size of fruit at the time of picking. 
Also where the trees were heavily loaded premature dropping of fruit 
was noticed after the foliage was seriously injured. The red spiders 
appeared on the foliage very soon after the leaves were out in the spring, 
having over-wintered in the egg stage on the bark, and were present 
in increasingly large numbers on both surfaces of the leaf throughout 
the season. No accurate data were obtained concerning the number of 
generations during the summer, but individuals were able to pass from 
the egg to the adult stage in from two to three weeks and the generations 
overlapped to such an extent that eggs and adults were always present. 
Thus the problem of control is in obtaining some material which will 
remain active upon the foliage for some time so that a second application 
after the eggs hatch will not be necessary. Several combinations of 
dust and spray have been used in an attempt to obtain the best control. 
Sulphur dust has been recommended by several stations as the best 
method of control. At least five different combinations of sulphur 
dust were used. 1. Sulphur dust alone; 2. Sulphur Arsenate of lead 
dust 90-10; 3. Sulphur, arsenate of lead-lime dust 75-10-15; 4. Sul¬ 
phur dust with 1% nicotine; and 5. Sulphur dust with 3% nicotine 
sulphate. The dust was applied from both sides of the row, there was 
