24 



OTRTER-SHELL BARK-LOUSE. 



3 



Explanation of figures— 1, ege, scarcely one hundredth of an inch in length ; 2, yoarglarva in 

 its active 'htnge ; 3, its appearand' sion after becoming fixed ; 4, appear.mce of seal? after the 

 second plate is formed ; 5 and 6, insect at difl'erent stages, as seen under the scale ; 7, fully formed 

 scale with inclosed insects, as .-een from below : 8, antenna, highly magnified. The side figure 

 shows the natural appearance of the scales on the tree. 



THE OYSTER-SHELL BARK-LOUSE. 



{Myiilaspis conchiformis, Gmelin.) 

 Order of HOMOPTERA. Family of Ooccid^. 

 Harris's Treatise, page 252 ; Fitch's 1st and 2d N. Y. Rep., p. 31 ; Walsh's 1st Ill- 

 Rep., p. 34; Riley's 1st Mo. Rep., p. 7. 



The common Aj^ple-tree Bark-louse, obscure and un- 

 inviting as it at first sight appears, is, in many repects, 

 one of the most anomalous and interesting insects that 

 comes under the cognizance of either the scientific or the 

 practical entomologist. How it is propagated, how it 

 obtains its nutriment, and how it migrates from one tree 

 to another ; whether it flourishes best on a healthy or a 

 debilitated tree, whether it exercises any selection 

 amongst the different varieties of apple, and whether, 

 with respect to its prevalence, it is upon the increase or 

 the decrease, are questions which have long been in- 

 volved in much obscurity, and some of which are yet 

 tar from being satisfactorily solved. Yet it is an insect 

 which has been long known, having been originally imported in- 

 to this country from the other side of the Atlantic, and has been 

 Bubiected to the prolonged scrutiny of some of th eacutest ento- 

 mologists that either Europe or this country has produced. 



It is one of the opprobria of entomology that the male of the 

 Oyster-shell Bark-louse has never been discovered. Judging from 

 the analogy of other species of the same genus, the male, if ever 

 discovered, will be found to be a very small two-winijed insect, 

 yet having no special affinity with the dipterous order of insects. 



