236 Forty-first Report on the State Museum. 



the bark beneath, becomes diseased, and is ultimately found dead 

 through to the wood. The next season these depredations are 

 repeated, but the new scales are attached between the old ones. On 

 the third year, on trees which are made the special point of attack, 

 the entire bark of the tree is so spotted by the minute dead spots that 

 a general roughness of the bark is noticed, presenting an unhealthy 

 and unsightly appearance in the orchard, and nothing is left to be 

 done but the removal of the trees." 



Description of the Scale. 

 The scales of the female, which are by far the most conspicuous and 

 abundant, are about one-twelfth of an inch long, narrow, and pointed 

 at the apex, rounded at the other extremity and broadest centrally, 

 and ordinarily somewhat curved. This particular form, so much like 

 that of an oyster or mussel shell, was indicated in the specific name of 

 conchiformis which it for a long time bore, and under which it was 

 frequently written of in former years, in connection with its then 

 generic reference' of Aspidiotus, even so recently as during the Reports 

 of Dr. Fitch. Its common name at that time was "the oyster-shell 

 bark-louse" — now it is known as "the apple-tree bark -louse." Its 

 color is brown, or ash-gray, nearly approaching that of the bark, except 

 at the apex, where it bears two of the cast-off coverings of the young 

 insect, which are of a dull yellowish or horn color. The scale of the 

 male is much smaller, nearly straight, and bears but a single molted 

 skin on its apex. 



Of the Insect and its Changes. 



These scales are not the insect or portions thereof, for the scale- 

 insect may, in its earlier stages, be found beneath them, but are a 

 thin pellicle which has been excreted by the insect for its covering and 

 protection, and thrown out in successive layers, as may be seen under 

 a magnifier, and built up by degrees, very much as is the shell of an 

 oyster. 



The several changes that the insect undergoes, from the time of its 

 hatching from the eggs beneath the scale, through its brief period of 

 free and active life, followed by its attachment to the bark where it 

 becomes permanently fixed, its subsequent moltings, the excretion of 

 the scale and its steady growth until it attains its full size, and the 

 mother has placed beneath it a hundred or more minute white eggs — 

 all these form an exceedingly interesting narration, but it has been so 

 often given that the reader who would know the details, is referred to 

 the rejjorts of Harris, Fitch, Walsh, Le Baron, Riley, and others, and 

 the pages of many of our agricultural papers. 



