22 



CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



the buds are swelling noticeably, and the weather must be warm at 

 the time in order to allow the oil to penetrate into the buds and kill 

 the mites. 



Rust Mite 



A very small mite, not unlike the pear leaf blister mite, is often 



found on the under surfaces of apple and pear leaves as well as on 



prune leaves. This is the rust mite (Phyllocoptes schlechtendali Nal.), 



so named because its feeding usually produces a rusty appearance on 



the leaves. It also 

 causes the leaves to 

 roll longitudinally. 

 At times the fruit 

 also is attacked and 

 may become russeted. 

 The mite itself is 

 slightly smaller than 

 the blister mite and 

 can scarcely be seen 

 with the naked eye. 

 Under a lens it is 

 found to be some- 

 what shorter and 

 more triangular in 

 shape than the blis- 

 ter mite. Instead of 

 producing blisters, 

 this mite feeds on 

 the leaf surface dur- 

 ing the growing sea- 

 son and hibernates 

 in the buds. It may 

 be controlled by the 

 same means used for 

 the blister mite; and 

 since it is exposed 

 during the summer, 

 sulfur or oil sprays 

 applied during that 

 time will also effect 

 control if care is used 

 to spray the under- 

 sides of the leaves 

 very thoroughly. 



Rosy Apple Aphid 

 The rosy apple 



aphid (Anur aphis 

 roseus (Baker)) curls the leaves, particularly those on the fruit spurs, 

 and infests the young fruit, causing it to become stunted and distorted 

 (fig. 24). These " aphid apples" do not thin out normally during the 

 "June drop" and clusters of them are often conspicuous in the fall, 

 especially on the lower and inner parts of the trees. At times they 

 are sufficiently numerous to cause a distinct reduction in the mar- 

 ketable crop. This aphid was probably introduced from Europe. 



Figure 24. — Apples stunted by the rosy apple aphid. 



