EXPERIMENT STATION BULLETINS. 581 



This scale, though everywhere present and sometimes very destructive, 

 more often attacks trees that for some reason are unhealthy and which 

 are therefore poorly fitted to support the extra drain of the scales. A 

 strong, healthy tree can usually bear the presence of a few of these 

 insects without much apparent injury, and they may be present for years 

 in small numbers without multiplying sufficiently to do much injury. 

 When, however, they become very numerous and seem to threaten the 

 tree, they can be easily checked by a spray of whale-oil soap or potash, 

 or by a spray of kerosene-emulsion when the newly-hatched lice are run- 



Fig. 10. Oyster-shell Bark-louse (Mytilaxpis pomorum). 



ning about and before they have grown a covering for themselves. This 

 time is usually during the last of May or the first of June, — the proper 

 time can be exactly determined by closely watching the trees. Just as 

 soon as the young lice are seen to be issuing from the scales it is time 

 to spray. The young lice will appear as very small insects, about as 

 small as can be seen by the unaided eye, and as they commence to secrete 

 the scale almost immediately on coming out, the remedy must not be 

 delayed. Use kerosene-emulsion, diluting about twelve times with water 

 (Hubbard formula, or the same per cent of kerosene with any other 

 formula). Another good practice is to scrape the scales from the limbs 

 and then wash with kerosene-emulsion or strong soap solution. 



WHITE SCALE OF THE PINE, 

 (Chiormspis pinifolii Fitch.) 



This pretty little scale is found on the leaves of almost all our species 

 of pine and spruce. It is pure white except for the amber exuviae at the 

 base. The adult female scales are usually long and slender and measure 

 about three mm. (| inch). The males are somewhat smaller and possess 

 only one cast-skin. While this scale does not often kill trees, it serves as 

 a representative of the scale-insects, and is such a common species that 

 anyone desirous of becoming acquainted with their appearance ea"n 

 readily obtain a supply. 



SCURFY SCALE OF THE PEAR AND APPLE. 

 (Chionaspis furfurus.) 



The scurfy-scale of the pear and apple can readily be distinguished 

 from the other species likely to be found on the same hosts by its white 

 color. It is from two to three mm. in size, and before it becomes cor- 

 roded and soiled by the weather is snowy white except at the base, where 

 the exuviae are placed. 



