310 AMERICAN POMOLOGY. 



them to do immense damage, as is true of the Aphides 

 and CoccidcB, the Tingis, the Tettigonia vitis, called 

 the Thrips by our vine-dressers ; and still more so of the 

 Chinch -bug of the Western prairies, which destroys whole 

 crops of our most important cereals. 



The colored juice of some bugs is used in the arts. 

 The coccus of the prickly pear, in Central America, is 

 gathered and dried to form the cochineal of the shops. 



Hemipterous insects are divided into two groups. True 

 bugs, called Hemiptera heteroptera, having the wing-cov- 

 ers opaque at the base, and laid horizontally, and crossing 

 each other obliquely at the end, overlapping; and the 

 Harvest-flies, such as Plant-lice and Bark-lice. These, the 

 Hemiptera homoptera^ have the wing-covers of one tex- 

 ture throughout, not horizontal, but more or less sloping, 

 and not crossing one another behind. Among these, 

 which all feed upon plants, some very troublesome pests 

 will here be noticed. 



COCCIDANS. BARK-LICE. 



Aspidiotus conchiformis, or the Apple Bark-louse, is 

 very numerous in many parts of our country, particularly 

 north of latitude 40 degrees. It commits sad devasta- 

 tions in some sections. Individually, it is but a little 

 scale ; but these animals are wonderfully prolific and soon 

 cover every twig of the tree, obstructing its transpirations, 

 and abstracting its vital juices; the leaves, and even the 

 fruit are overrun with these miserable scales, but the twigs 

 are their favorite resort. These scales are oblong, shaped 



