CHAPTER XXII 



Some Insect Pests of Cultivated Plants 



By W. E. Britton 



State Entomologist, Agricultural Experiment Station, New Haven, Conn. 



The Life of an Insect — Spraying Equipment — Materials Used 



to Control Insect Pests — Fumigants — Insect Pests Arranged 



by Host Plants 



THERE is scarcely a crop grown which is not attacked and injured by 

 insects. It has been estimated that at least one-tenth of all crops 

 in the United States is destroyed each year by insects. This total 

 damage amounts to fully $1,000,000,000.00 annually. 



This article has been prepared so that the amateur may have a simple 

 guide at hand for convenient reference. A part of the material and illus- 

 trations have appeared in the Spray Calendar published by the Connecti- 

 cut Agricultural Experiment Station, and are here printed, by permission, 

 in somewhat different form. 



The Life of an Insect 



Insects are very abundant and occur everywhere. Though some are 

 called injurious because they attack and injure or destroy plants or plant 

 materials, or infest animals which man has raised for his own use, there are 

 many beneficial insects: some furnish food, like the honey bee, some provide 

 clothing material, like the silkworm, many are parasites upon noxious in- 

 sects, and many species of bees pollinate the flowers of fruit and garden 

 trees and plants, thus assuring a crop. Most insects have four distinct 

 stages in their cycle of development: 



1. Egg 



2. Larva (caterpillar, grub, maggot, etc.) 



3. Pupa (chrysalis) 



4. Adult 



In several large groups, including the grasshoppers, true bugs, aphids, 

 scale insects, etc., the insects do not pass through the distinct larval and 

 pupal stages but undergo a gradual development from the time they 

 hatch from the eggs until the adult stage is reached. 



Insects may be div ided roughly into biting or chewing (like the Colorado 

 potato beetle) and sucking (like the aphids and scale insects). Against the 

 former we can use arsenical poisons, but to kill the latter we must use con- 

 tact insecticides. Both may be killed with fumigants. The two forms are 

 illustrated on page 308. 



Spraying Equipment 



Every one who grows plants should be provided with some convenient 

 form of pump for applying sprays and should keep in stock a few of the 

 materials most often used, so as to be available at a moment's notice when 

 needed. 



For the small garden, one of the most convenient pumps is the small 

 compressed air outfit holding from three to four gallons. If a knapsack 

 sprayer or bucket outfit be possessed, either can be made to answer the 



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