"WHITE PINE LEAF-LOUSE. 87 



whilst he corrected the errors of his predecessors, failed himself 

 to detect the radical difference in the nature of the anal sack as 

 compared with the larval and medial scales. 



We have thus far spoken only of the female insects and their 

 scales, but in addition to these we find upon the leaves about an 

 equal number of a much smaller scale, being only one-half as long 

 and scarcely half as broad ; straight, linear, and carinated. This 

 is the scale of the male insect. It is found, upon examination, to 

 be composed of only two of the corresponding parts of the female 

 scale, namely, the larval scale and the anal sack, the medial scale, 

 and that stage of growth indicated by it, being absent. Accord . 

 ingly it attains its growth in a shorter period than that of the fe- 

 male, requiring only about ten days for its completion. Ttie 

 male of this species is deserving of special interest, from the fact 

 that, this sex, in the more widely known Bark-louse of the apple 

 tree, has never been discovered. From the similarity of the two 

 species in all their important characters, eo far as they are known, 

 it is reasonable to assume that the male of the Aspidiotus (or as it 

 is now called, Mytilaspis) conchiformis^ if it ever be discovered, 

 will be found to resemble, in all essential characters, the male of 

 the Mytilaspis of the Pine. 



The first sight that I obtained of this interesting insect was on 

 the 19th of August, when, upon raising a number of the small 

 linear scales, I detected under one of them a male individual, in a 

 condition analagous to the pupa state, with its rudimental limbs 

 lying flatly upon its sides, and with a short, obtuse, and but hal f 

 developed style projecting from its anal extremity. On the 23d 

 of the same month, I saw a fully developed specimen after it had 

 emerged from its cocoon-like scale, and for two weeks following 

 this, any number of them could be obtained by inclosing the infes- 

 ted leaves in a closed bottle. 



It will be borne in mind that the minute larvae of this very 

 anomalous tribe of insects, enjoy but a very brief period of active 

 life; that they move about over the adjacent leaves and twigs 

 for a time, rarely exceeding two or three days from the time they 

 leave the Q^g^ and then fix themselves immovably. At this inci- 

 pient stage of their existence the two sexes cannot be distinguished 

 from each other. But as soon as they become fixed and begin to 



