Plants as Affected by Animal Parasites. 173 



prevent the heavier part of the spraying mixture from 

 settling. 



Excellent bellows and force pumps, designed ex- 

 pressly for applying insecticides, are now 

 manufactured. 



305. The Use of Insecticides. In treat- 

 ing any given insect, the most important 

 question to decide, is the manner in which 

 it appropriates its food, as upon this will 

 depend the preventive measures to be 

 used. 



306. Injurious Insects are refer- 

 able to Two Classes, viz., 

 eating insects, i. e., those 

 feeding directly upon the 

 plant tissues, as the potato 

 beetle, the apple-tree borers,* 

 the plum curculio;f and the 

 i sucking insects, i. 



e., those feeding 

 only upon the 

 juices of the plant, 

 as plant lice, the 

 squash-bug,J and 

 the oyster-shell 

 bark-louse. 



307. The Eating 

 Insects may be 

 subdivided into leaf-eaters, those that devour the foli- 



* The round-headed apple-tree borer. Saperda Candida; the flat- 

 headed apple-tree borer, Chrystibothrix ffinorata. 



\Conotrachelusnenuphar. f Anaxa trutis. $ Mylilaspis pomorum 



FIG. 71. Steam 

 factored by (the 

 Rochester, N. Y. 



spraying outfit, manu- 

 Shipman Engine Co.. 



