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, ao-reeino- 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withdrawn beneath the shell of the bodv and concealed, 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 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 
antennae, 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- 
xime of the “New England Farmer,” pp. 186, 187. 
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