210 SCALE-INSECTS, BARK-LICE, MEALY-BUGS. 
gall-like form, and is covered with larger or smaller scales of 
wax, which may be in the form of powder, of large tufts or 
plates, of a continuous layer, or of a thin scale. Beneath this 
protecting substance lives the insect. The illustrations of the 
different species described will give a better idea of these peculiar 
and destructive insects than mere words. 
During the last years considerable attention has been paid 
to these insects, not alone to study their peculiar life-histories, 
but also to devise methods to destroy them. Prof. Comstock 
especially has given us most excellent descriptions. 
All scale-insects are plant-feeders, and like the plant-lice 
obtain liquid food by means of suction. But not all are injuri- 
ous, as some furnish dye-stuffs, shellac, or wax. The Cochineal 
Insect, illustrated in Fig. 167, furnishes a beautiful color. 
Prof. Comstock aud others divide this family into four sub- 
families, three of which are found in Minnesota: 
“A. Body either naked or clothed with a secretion; 
the clothing, however, not in the form of a scale 
composed in part of moulted skins. 
B. Body of female usually remaining distinctly 
segmented, and retaining the power of mo- 
tion till maturity; sometimes, however, it 
becomes more or less globular and fixed, but 
in all cases the labium is composed of several 
segments, and there are no anal plates. The 
abdomen usually ends in a pair of lobes, each 
furnished with one or more bristles........ COCCINA. 
BB. Body of female changing much in form during 
development, becoming scale-like or more or 
less globular, with the segmentation absent 
or indistinctly indicated. The individuals 
usually become fixed to the plant upon which 
they live; sometimes they are enclosed in a 
covering of wax. In all cases the labium is 
composed of a single segment; the caudal 
opening of the alimentary canal in the adult 
female is covered by a pair of subtriangular 
Plates sas td we cen e tO ape Sites an ree ee LECANINA. 
