302 



BOARD OF AGRICULTURE. [Pub. Doc. 



usually of a light, dirty-gray color. The oyster-shell bark 

 louse (Fig. 3) also occurs on the apple, pear, etc., and on 

 ash, willow and poplar as well. This insect differs from the 

 preceding species in that the scale is more elongate, and 

 usually curved. The molted skin of each insect forms a 

 protuberance at its apex. In Massachusetts these two in- 

 sects are seldom dangerously injurious, and when over- 

 abundant may be destroyed by the application of simple 

 remedies. 



Fig. 3. Oyster-shell bark louse {Mytilaspis pomorum) : a, female scale from below, 

 showing eggs; b, female scale from above, both figures greatly enlarged; c, female scale; 

 »/, male scale, enlarged ; e„male scales on twig, natural size. From Howard, Year Book, 

 U. S. Department of Agriculture, 1894. 



The San Jose scale (Fig. 1) is distinguished from the pre- 

 ceding insects by its nearly circular outline, its dark-gray 

 color and the nipple-like projection at its centre, as shown 

 in the illustration. The male scales are more numerous and 

 are smaller and darker than the female scales, bearing a dis- 

 tinct white dot in the centre of the protuberance. The 

 farmer should be able to distinguish between these three 

 scales without the aid of a lens. Unfortunately there are a 



