NEW YORK EXPERIMENT STATION BULLETIN 373 



the yonnjr scales, altliough not protected by a scaly covering, are not 

 easily rubbed off and hence may remain on trees shipped long distances 

 without injury. 



Remedial measures. — In the report abo/e referred to we have given 

 a detailed account of a series of experiments with kerosene emulsion as a 

 remedy for this species. It was found that kerosene emulsion diluted 

 with from four to six parts of water could be depended upon to kill the 

 hibernating scales when ai)plied to the infested trees in the form of a 

 spray. When the spray is to be directed against the newly hatched 

 lice, the emulsion should not be diluted with more than nine i)arts of 

 water. 



THE OAK SCALE. 

 Asterodiaspis quercicola Bouche. 



There are but few references to this insect in the writings of American 

 entomologists. In his report for 1880, p. 330, Prof. J. H. Comstock, 

 who was then Entomologist of the United States Department of Agri- 

 culture, published a description of the male and female, the former being 

 taken from Signoret. Another reference is in Insect Life, Vol II, p. 41, 

 in which Dr. L. O. Howard states that this scale is found almost solelv 

 upon American oaks in a grove in the Department grounds, previously 

 referred to by Prof. Comstock in his report for 1880. In Insect Life, Vol. 

 VII, p. 120, Mr. C. L. Marlett gives the result of experiments against this 

 insect. He found that the newly hatched young could be killed by spray- 

 ing the infested trees with kerosene emulsion, 1 part to 13 parts of water. 

 In the same volume, page 428, a brief reference is made to a note by 

 Mr. E. Newstead in the Entomologist's Monthly Magazine for April, 

 1895, in which he states that, although birds are not usually supposed to 

 feed on scale insects, he had found that the blue tit and longtailed tit 

 feed on this and certain other species. 



It is probable that, except in isolated cases, the species has never been 

 a serious pest in this country. 



As its name implies this scale attacts the oak. Some idea of its gen- 

 eral appearance can be had by referring to Plate I, fig. 6. This figure is 

 from a photograph of an infested twig, natural size. The female scales 

 are nearly circular and somewhat conical. They are dark or yellowish 

 green in color. When one of the mature scales is removed, it will be 

 found to have made a pit-like depression in bark. The mature female 

 scales will measure from 1 mm. to nearly 2 mm. in diameter. According 

 to Signoret, as quoted by Comstock, the male scales are oval and usually 

 smaller than the females, measuring but 1 mm. in length. But little is 

 known of the life history of this species. 



We have seldom found this scale in the nursery. It may do serious 

 injury on large trees, however. A good illustration of this is on one of 

 the principal streets of Geneva, where most of the English oaks, Querciis 

 rohar, which line the streets for two or three blocks on either side, have 

 been either killed or nearly so by this scale. So far as we know its only 

 food plant is the oak. 



