72 WILSON & TOOMKIt FKIiTI Ll/KK COMPANY 



Chapter XII 



Insects in General 



Practically, insects can be divided into four classes 

 chewing insects that may be killed with stomach poison; 

 sucking insects that may be killed with contact insecti- 

 cide; insects like the weevil, the habits of which make 

 fumigation necessary ; and others like the plant bug and 

 leaf hoppers, which even to check materially take all of 

 man's wit. 



The chewing insect can be distinguished from those 

 which suck, by the mouth parts, the one having jaws, 

 "mandibles," that work sideways, and the other a snout 

 for piercing vegetable tissue. The most of the insect 

 damage to our crops is done by the young or larviP. 

 Many are then popularly called "worms." Our cabbage 

 is eaten by the young of a dainty white butterfly; wire 

 worms are the offspring of beetles ; while a fly much like 

 the common house fly lays the eggs that hatch into root 

 maggots. Broadly speaking, insects in the larval stage 

 do us no good and do harm in proportion to their 

 number. 



If chewing insects feed in the open they can be killed 

 with stomach poisons; for this either Paris green or 

 arsenate of lead is generally used. Sucking insects, com- 

 mon examples of which are the aphids or plant lice of 

 the garden, the different scales on various trees, and the 



