306 OHIO EXPERIMENT STATION: BULLETIN 332 



of the dead females still adhere to the host, some persisting until 

 the following year. 



Nature of work. The writer has never observed a tree killed 

 by the burr oak kermes, but it is no uncommon sight to find dead 

 twigs. Unquestionably the presence of the insect in numbers is 

 perceptibly devitalizing to the host and the unhealthy, distorted, 

 unnatural appearance of the foliage detracts greatly from its nat- 

 ural beauty. In Ohio where the pest abounds it may be considered 

 an important if not the most important enemy of the burr oak. 



Food plants. The burr oak (Quercus macrocarpa) is the more 

 common host of this species, but other oaks as follows, have been 

 recorded: Chinquipin oak (Q. prinoides) ; white oak (Q. alba) ; and 

 red oak (Q. rubra). 



Distribution. In Ohio this insect is known to occur in Colum- 

 bus and Cincinnati, having rather wide distribution in the parks of 

 the latter place. It is reported also from Indiana, Massachusetts, 

 Kansas and Kentucky. 



Natural enemy. A red mite was observed by the writer to> 

 feed with avidity upon the emerging males August 4, 1913. 



Control. On March 27, 1915, and April 4, 1916, the writer 

 sprayed burr oaks in the Cincinnati parks, badly infested with the 

 burr oak kermes. Scalecide 1 part to 15 parts of water was used. 

 In the first instance the work was done with the ordinary type mist 

 sprayer, but in the second the solid stream type, equipped with a 

 three-sixteenths of an inch nozzle was used. The trees sprayed in 

 1916 were from 65 to 70 feet high. 



In both the foregoing instances the control was absolute. The 

 trees sprayed in 1916 were not sprayed in 1917. In May, 1918, they 

 were again examined and were found not only to be practically free 

 from the scale, but also had in some measure recovered from the 

 effects of the previous attack while the nearby trees, reserved 

 checks were very Dadly infested. It may be stated, therefore, that 

 miscible oil, applied in the spring before the foliage starts, is 

 satisfactory control agency for this species. 



THE PIT-MAKING OAK SCALE 



(Asterolecanium variolosum Ratz.) 



Description. The pit-making oak scale is one of the most dis 

 tinctive of the scales occurring in Ohio. It is also known by some 

 as the golden oak scale ; both names being well suited to the insect. 

 A glance at Plate LVI, Fig. 1, conveys an idea of the pit-making 

 propensities of the species, the twigs and branches of the hosl 

 appearing strongly poc-marked when infested. The illustration 

 does not bring out the beautiful greenish-golden coloration of th< 



