'580 STATE BOARD OF AGRICULTURE. 



THE ECCENTRIC SCALE. 



(Aspidlotus ancylus Put.) 



The nearest relative to the San Jose" scale that we have in Michigan is 

 the eccentric scale or Putnam's scale (Aspidiotus ancylus). Indeed, the* 

 resemblance is so close that it requires a careful examination to dis 

 •criniinate the two species. The scale of the adult female (Fig. 9, 1) is grey 

 in color and nearly circular in form, though sometimes wider than long. 

 The cast skins are almost always considerably to one side of the center 

 or eccentric with the margin. The color of these cast skins or exuviae is 

 usually brick-red, though they are ordinarily obscured by a secretion 

 which is formed over them. The scale of the female is from one mm. to 

 two mm. in size. The male scale (Fig. 9, 2) is smaller than that of the 

 female and somewhat elongated, but otherwise resembles it. 



The effect of large numbers of these scales cannot be otherwise than 

 injurious, although trees seem to support a few without injury. The 

 great range of food-plants on which the eccentric scale feeds makes it 

 very difficult to eradicate. In this respect it is very like the San Jose" 

 scale. It is, however, an old stand-by; like the oyster-shell bark-louse, 

 it has been here for a long time and is likely to be found on almost any 

 apple, peach, plum or pear tree. It is also found on maple, hackberry, 

 ash, and elm, besides a number of other trees and shrubs. Fortunately, 

 although widespread, it is little to be feared, for it seldom becomes 

 troublesome and then can be killed easily by the same methods employed 

 against the San Jose" scale. 



The constant differences that distinguish the eccentric scale from the 

 'San Jose" scale lie in the arrangement of the fringes on the last segment 

 of the insect under the scale. These can be seen only with a compound 

 microscope, and 1 then the specimens require careful preparation. It is 

 always best to resort to the compound microscope in settling these points, 

 .in order to be certain and to avoid the labor and expense which would 

 follow the confounding these two species. 



THE OYSTER-SHELL BARK-LOUSE. 



(Mytilaspis pomorum.) 



Perhaps no other insect has been received by mail in greater numbers 

 •during the past season than the oyster-shell bark-louse (Mytilaspis 

 pomorum). Although this scale without doubt has been a resident of 

 Michigan almost from time immemorial, it has been brought to the front 

 lately in unusual quantities because of its being mistaken for the San 

 Jos6 scale. All scales look very much alike to the uninitiated and the 

 oyster-shell scale is almost sure to be found wherever apple-trees exist. 

 Fig. 10 will give an idea of the general appearance of the insect. 



