INSECT PESTS OF OHIO SHADE AND FOREST TREES 285 



trees with very dark-colored bark. On trees with lighter bark, this 

 characteristic it not so pronounced, the scales standing out with 

 considerable prominence. 



The female scale is about one-tenth of an inch in diameter, 

 almost circular in form and dark gray in color. The exuvium is 

 jet black, particularly when rubbed. The scale covering is harder 

 and more rigid than the average. When removed from the bark 

 it leaves a decided white spot. 



The male scale is smaller, oval and convex anteriorly. It is of 

 the same color of the female. (See Plate XLVII, Fig. 4.) 



Nature of work. — The bark of twigs, limbs and branches is 

 infested by this scale, and the injury frequently is sufficient to cause 

 the death of the host. In other cases only branches and limbs 

 succumb. A tendency toward clustering is noted with this species, 

 particularly when it is infesting beech. An unusual type of injury 

 to beech was noted in 1914 in Burnett Woods and other parks in 

 Cincinnati. There the infestation assumed the shape of bands an 

 inch or less in width around the smaller limbs, and beyond the 

 collar of scale the limbs were dead. Limbs from li/^ to 2 inches in 

 diameter seemed more susceptible to injury of this sort than those 

 of any other size. 



Food plants. — Oaks are more generally considered the favorite 

 host of this species, but in the region of Cincinnati beech seems 

 preferred. At any rate it suffers to a greater extent than any 

 other plant. The hosts reported are as follows: Hickory, grape- 

 vine, beech, willow oak (Quercus phellos) , Quercus coccinae, Q. 

 acuminata, Q. ynacrocarpa, pecan {Hicoria ovata) and maple. The 

 writer has also taken this species upon English walnut. 



Distribution. — The obscure scale is more abundant in southern 

 than in northern Ohio. In some sections of the southwestern part 

 of the State it is very abundant, invading both urban and rural dis- 

 tricts. The species is very abundant in the southern states and 

 extends westward to include those of the west-central group. 



Control. — In the writer's experience 33° lime-sulphur used at 

 the rate of 1 to 7 and applied in the spring has failed to control this 

 species. Miscible oil used at the rate of 1 part to 15 of water and 

 applied at the same time gave favorable results. Only a few young 

 scales developed during the following season on trees so treated 

 while new scale was abundant on nearby unsprayed checks. 



THE OYSTER SHELL BARK LOUSE 



(Lepidosaphes uhni Linn.) 



The oyster shell bark louse is almost as widely distributed as 

 the San Jose scale but while the San Jose scale is largely a fruit tree 



