Insect Pests and Plant Diseases. 177 



prepared by an authority in that particular field. Study and follow the 

 directions carefully, apply the remedies in time and with thoroughness, 

 and in case of failure or difficulty write to the Cornell Agricultural 

 Experiment Station for assistance. 



11. INSECTS AND THEIR CONTROL. 



M. V. SLINGERLAND and C. R. CROSBY. 



For purposes of control, insects are divided into two great classes: 



A. Chezving insects, or those having jaws by means of which they 

 bite off and eat portions of the tissues of the plant. Examples : Potato 

 beetle, (Fig. 145) canker-worm and codling-moth caterpillar. 



B. Sucking insects, or those furnished with a beak containing four 

 bristles united into a slender tube. The bristles are inserted into the 

 plant and through them the insects 

 suck out the sap. Examples : Squash 

 stink-bug, San Jose scale and plant- 

 lice (Fig. 146). 



Chewing insects are usually 



controlled by applying to their 



food poisons such as Paris green, 



arsenate of lead or hellebore. 



Sticking insects cannot be reached 



^1 . J ^ 1 I -11 1 L Fig- 146. A plant-louse, one of the suck- 



in this way and must be killed by j„^ -^^^^^^^ showing the beak. 



a direct application of contact 



insecticides, such as soaps, oils or othef substances. In fighting sucking 



insects, thorough and skillful work is required since every individual 



insect must be hit by the spray, while in the case of chewing insects, 



it is merely necessary to apply the poison thoroughly to the food-plant. 



APPLE. 



The small brown caterpillars with a black head devour the 

 Bud-moth. tender leaves and flowers of the opening buds in early spring. 



Make two applications of either i lb. Paris green or 4 lbs. arsenate 

 of lead in 100 gals, of water; the first when the leaf-tips appear and the second 

 just before the blossoms open. If necessary, spray again after the blossoms fall. 

 For use with Borcdaux, see apple scab, Cornell Bulletin 107. 



These caterpillars are small measuring-worms or loopcrs that 

 Canker-worms, defoliate the trees in May and June. The female moths are 



wingless and in late fall or early spring crawl up the trunks of 

 the trees to lay their eggs on the branches. Spray thoroughly once or twice, before 

 the blossoms open, with i lb. Paris green or 4 lbs. arsenate of lead in 100 gals, of 



