204 INSECTS INJURIOUS TO VEGETATION. 



change their skins and color repeatedly, and acquire wing- 

 scales, or rudimentary wings. They then fix themselves to 

 the bark in rows, and remain sucking the sap till their last 

 change approaches, at which time they disperse among the 

 leaves, cast off their skins, and appear in the winged form. 

 When considerable numbers attack a pear-tree, the latter soon 

 assumes an unhealthy appearance, its growth is checked, its 

 leaves and shoots curl up, and the tree dies by degrees, if not 

 freed from its troublesome guests. Kollar recommends brush- 

 ing off the insects, when young, with a brush of hog's bristles, 

 and crushing under foot those that fall ; and also advises to 

 search for the winged females in the spring, and destroy them 

 by hand. Such a process would be altogether too tedious 

 and uncertain here. I would therefore suggest the expedi- 

 ency of washing the tvvigs with a brush dipped in a mixture 

 of strong soapsuds and flour of sulphur. If this be done 

 before the buds expand, the latter will not be injured thereby, 

 while the application will be likely to deter the insects from 

 laying their eggs on the tree. A weaker application of the 

 same, or the common solution of whale-oil soap, may wsuffice 

 to kill the young insects after they have fastened themselves 

 upon the bark. If the latter be thrown upon the trees with a 

 syringe, it will destroy the insects on the leaves also. 



Others, both sexes of which are also winged, have long and 

 slender bodies, very narrow wings, which are fringed with fine 

 hairs, and lie flatly on the back when not in use. They are 

 exceedingly active in all their motions, and seem to leap rather 

 than fly. They live on leaves, flowers, in buds, and even in 

 the crevices of the bark of plants, but are so small that they 

 readily escape notice, the largest being not more than one 

 tenth of an inch in length. These minute and slender insects 

 belong to the genus TJirlps. Their punctures appear to poison 

 plants, and often produce deformities in the leaves and blos- 

 soms. The peach-tree sometimes suffers severely from their 

 attacks, as well as from those of the true plant-lice; and they 

 are found beneath the leaves, in little hollows caused by their 

 irritating punctures. The same applications that are employed 

 for the destruction of plant-lice may be used with advantage 



