HEMIPTERA. 203 



brush, and as high as practicable, so as to cover the whole sur- 

 face, and fill all the cracks in the bark. The proper time for 

 washing over the trees is in the early part of June, when the in- 

 sects are young and tender. These insects may also be killed by 

 using in the same way a solution of two pounds of potash in seven 

 quarts of water, or a pickle consisting of a quart of common salt 

 in two gallons of water. 



There has been found on the apple and pear tree another kind 

 of bark-louse, which differs from the foregoing in many important 

 particulars, and approaches nearest to a species inhabiting the 

 aspen in Sweden, of which a description has been given by Dal- 

 man in the " Transactions of the Royal Academy of Sciences of 

 Stockholm", * for the year 1825, under the name of Coccus cryp- 

 iogamus. This species, is of the kind in which the body of the 

 female is -not large enough to cover her eggs, for the protection 

 whereof another provision is made, consisting, in this species, of a 

 kind of membranous shell, of the color and consistence almost of 

 paper. In the autumn and throughout the. winter, these insects 

 are seen in a dormant state, and of two different forms and sizes 

 on the bark of the trees. The larger ones measure less than a 

 tenth of an inch in length, and have the form of a common oyster 

 shell, being broad at the hinder extremity, but tapering towards 

 the other, which is surmounted by a little oval brownish scale. 

 The small ones, which are not much more than half the length of 

 the others, are of a very long oval shape, or almost four sided 

 with the ends rounded ; and one extremity is covered by a minute 

 oval dark colored scale. These little shell-like bodies are clus- 

 tered together in great numbers, are of a white color and membra- 

 nous texture, and serve as cocoons to shelter the insects while 

 they are undergoing their transformations. The large ones are 

 the pupa-cases or cocoons of the female, beneath which the eggs 

 are laid ; and the small ones are the cases of the males, and differ 

 from those of the females not only in size and shape, but also in 

 being of a purer white color, and in having an elevated ridge pass- 

 ing down the middle. The minute oval dark-colored scales on 

 one of the ends of these white cases are the skins of the lice while 



* Kongl. Vetenskaps Acadern. Nya Handlingar. 



