204 INSECTS INJURIOUS TO VEGETATION. 



they were in the young or larva state, and the white shells are 

 probably formed in the same way as. the down which exudes from 

 the bodies of other bark-lice, but which in these assumes a regular 

 shape, varymg according to the sex, and becoming membranous 

 after it is formed. Not having seen these insects in a living state, 

 I have not been able to trace their progress, and must therefore 

 refer to Dalman's memoir above mentioned, for such particulars as 

 tend to illustrate the remaining history of this species. The body 

 of the female insect, which is covered and concealed by the outer 

 case above described, is minute, of an oval form, wrinkled at the 

 sides, flattened above, and of a'reddish color. By means of her 

 beak, which is constantly thrust into the bark, she imbibes the 

 sap, by which she is nourished ; she undergoes no change, and 

 never emerges from her habitation. The male becomes a chry- 

 salis or pupa, and about the middle of July completes its transfor- 

 mations, makes its escape from its case, which it leaves at the 

 hinder extremity, and the wings with which it is provided are re- 

 versed over its head during the operation, and are the last to be 

 extricated. The perfect male is nearly as minute as a point, but 

 a powerful magnifier shows its body to be divided into segments, 

 and endued with all the important parts and functions of a living 

 animal. To the unassisted eye, says Dalman, it appears only as 

 a red atom, but it is furnished with a pair of long whitish wings, 

 long antennae or horns, six legs with their respective joints, and 

 two bristles terminating the tail. This minute insect perforates 

 the middle of the case covering the female, and thus celebrates its 

 nuptials with its invisible partner. The latter subsequently de- 

 posits her eggs and dies. In due time the young are hatched and 

 leave the case, under which they were fostered, by a little crevice 

 at its hinder part. These young lice, which I have seen, are 

 very small, of a pale yellowish brown color, and of an oval shape, 

 very flat, and appearing like minute scales. They move about for 

 a while, at length become stationary, increase in size, and in due 

 time the whitish shells are produced, and the included insects pass 

 from the larva to the pupa state. The means for destroying these 

 insects are the same as those recommended for the extermination 

 of the previous species. 



Many years ago, when on a visit from home, I observed on a 



