HEMIPTERA. l6 5 
caused many species that infest cultivated plants to become 
world-wide in distribution. 
During recent years much attention has been paid to 
devising methods of destroying these pests. Various soapy 
Fig. 202. —The Scurfy Bark-louse. Chionaspts furfur us: 1. scales natural size; xa, 
scale of male enlarged ; x£, adult male enlarged ; 1 c, scale of female enlarged. 
or alkaline washes, and one made of lime, salt, and sulphur, are 
now used on the trees with deciduous foliage; the wash is 
applied during the winter while the trees are naked. In the 
case of orange and lemon trees, which are constantly clothed 
with leaves, a large tent is lowered over the tree and a 
