166 



Principles of Plant Culture. 



I 



ner in which it works its injury, as upon this will depend 

 the preventive measnres to be used. 



306. Injurious Insects are rel'erable to Two Classes, viz., 

 eaiiiig insects, i. e., those feeding directly upon the plant 

 w.f.#/ tissues, as the potato beetle, the apple-tree 

 l)urers,* the xjlum curculio; f and the suclc- 

 in[l inserts, i. e., those feeding only upon the 

 juices of the phmt, as plant lice, the squash- 

 Ijug, J and the oyster-sliell bark-louse. § 



307. The Eating Insects may be subdi- 

 vided into le((f-e(iters. those that devour the 

 foliage; root-eaters, tliose that devour the 

 roots: and burrowers, those that har- 

 lior witliin some part of the 

 l>lant by eating a passage for 

 their bodies. 



308. The Leaf-Eaters include 

 numerous species. They are 

 leadilj' recognized by the fact 

 that the leaves, on which they 

 feed, disappear 

 more or less rap- 

 idly. They may 

 generally be d e- 

 stroyed by apply- 

 ing a poison to the 

 foliage, for which 

 purpose the arsen- 



FIG.7L Steam spraying outfit, manufactured ^^^^ COmpOUnds are 

 by the Shipman Engine Co., Rochester, N. Y. well adapted (28-4) . 



In cases where the use of a deadly poison is unsafe, hel- 

 lebore (289) or pyrethrum (290) may be substituted. 



* The round-headed apple-tree borer, 8aperda Candida; the flat-headed 

 apple-tree borer, Chrysobothris feniorata. -f Conotrachelus nenuphar. 



X Anasa trlsiis, g Mytilaspis pomorum. 



