STRUCTUKE AND DEVELOPMENT OF INSECTS. 19 



Though arsenical poisons are generally used as sprays 

 for biting insects, soft-bodied caterpilhirs and similar larv^ae 

 are often killed by the use of contact insecticides, which 

 affect them the same as sucking insects. 



The reader will observe that, almost without exception, 

 the remedies advised for different insect pests in the fol- 

 lowing pages are determined by some peculiarity, either of 

 structure or develo^mient, of the insect to be combated. 



