BARK-LICE. 249 



only the Thola of the Phoenicians and Jews, the Kermes 

 of the Arabians, or the Coccus of the Greeks and Romans, 

 but the scarlet grain of Poland, and the still more valuable 

 Cochenille of Mexico, together with various kinds of bark- 

 lice, agreeing with the former in habits and structure. 



These insects vary very much in form ; some of them are 

 oval and slightly convex scales, and others have the shape 

 of a muscle ; some are quite convex, and either formed like 

 a boat turned bottom upwards, or are kidney-shaped, or 

 globular. They live mostly on the bark of the stems of 

 plants ; some, however, are habitually found upon leaves, and 

 some on roots. In the 'early state, the head is completely 

 withdrawn beneath the shell of the body and concealed, 

 the beak or sucker seems to issue from the breast, and the 

 legs are very short and not visible from above. The females 

 undergo only a partial transformation, or rather scarcely 

 any other change than that of an increase in size, which 

 in some species, indeed, is enormous, compared with the 

 previous condition of the insect ; but the males pass through 

 a complete transformation before arriving at the perfect or 

 winged state. In both sexes we find threadlike or tapering 

 antenna3, longer than the head, but much shorter than those 

 of plant-lice, and feet consisting of only one joint, terminated 

 by a single claw. The mature female retains the beak or 

 sucker, but does not acquire wings ; the male on the con- 

 trary has two wings, but the beak disappears. In both 

 there are two slender threads at the extremity of the body, 

 very short in some females, usually quite long in the males, 

 which moreover are provided with a stylet at the tip of the 

 abdomen, which is recurved beneath the body. 



The following account * contains a summary of nearly all 

 that is known respecting the history and habits of these 

 insects. Early in the spring the bark-lice are found appar- 

 ently torpid, situated longitudinally in regard to the branch, 



* It was drawn up by me in the year 1828, and published in the seventh vol- 

 ume of the " New England Farmer," pp. 186, 187. 

 32 



