MEANS OP CONTROLLING INSECTS 



43 



sects are starved out by finding their favorite 

 food-plant replaced by some crop they do not like. 

 Many field crops may suffer for a season or two 



. Fig. 64. Jatiing leacb tree foi curculio. 



from wireworms or white grubs if planted in fields, 

 as pastures or old meadows, that have been in 

 sod for several years and are the favorite breed- 

 ing grounds of these pests. But thorough cultiva- 

 tion of such crops will soon discourage the insects. 

 Clean culture, or the destroying of weeds and 

 clearing away of rubbish, will often help in the 

 warfare against insect pests. Many insects find 

 favorable hibernating quarters in rubbish, old stone 

 walls, near-by clumps of bushes or forest lands. 

 One fruit-grower has largely eliminated the plum 

 curculio from his peach orchard by planting it 

 away from such favorable hibernating quarters. 

 The removal or burial of old cabbage stumps, old 

 squash or cucumber vines, and other garden refuse, 

 so as to leave the ground clean in the fall, will 

 help much in controlling garden insects, like the 

 cabbage, radish- and onion-maggots, cutworms, and 

 other serious pests. Sometimes an attractive plant 

 is used early in the season as a decoy, to be de- 

 stroyed when it has served its purpose and become 

 well infested with the pest. Then the main crop to 

 be protected is planted later and often escapes 

 serious infestation. A strip of mustard or early 

 cabbages may be sown early in spring to attract 

 the hibernated harlequin-bugs, which can then be 

 killed with kerosene before the main crop of cab- 

 bage is put out. A strip of wheat sown in August 

 will often attract a large proportion of the autumn 

 brood of the hessian fly. This infested strip can 

 then be plowed under in September, or just before 

 the whole field is prepared 

 for the main crop, which 

 should be delayed in 

 planting as long as local 

 conditions will permit. 

 This "farm practice" 

 method of an early decoy 

 strip and late planting 

 will usually circumvent 

 this serious wheat, barley 

 and rye pest. Gardeners 

 « <:= < i,..«^ ,>„» Af tt,. who grow cucurbitaceous 



Fig. 65. A beetle, one of the . » . , , 



chewing insects. Cneum- Vines sometimes plant a 

 ber beetle (Epitrix cu- gtj.Jp gf garly squashes 



eumens). Adult beetle »^ -j » .i. £ u 



much eniareed. along One Side of the held 



and delay putting out the main crop, so as to at- 

 tract many of the striped beetles, stink-bugs and 

 borers to the decoy strip. 



Extensive investigations have demonstrated that 

 the cotton boll-weevil can be controlled only by 

 cultural methods. Profitable crops of cotton can 

 be grown in spite of the weevil by planting early- 

 maturing varieties farther apart and earlier, by 

 thorough cultivation, by plowing up and destroying 

 all the old stalks in early autumn, and by a more 

 liberal use of fertilizers — all these are " farm prac- 

 tices." By burning fruit-tree prunings before spring, 

 the hibernating stage of several fruit pests, as 

 plant-lice eggs and bud-moth larvae, may be de- 

 stroyed. The application of a little quick-acting 

 commercial fertilizer will sometimes stimulate a 

 plant to overcome or outgrow the onslaught of its 

 insect enemies ; but when used in practicable or 

 fertilizing quantities, these fertilizers will not kill 

 the insects. 



It is an alluring thought that we may be able 

 to develop insect-resisting varieties of many kinds 

 of agricultural plants. The resistance of certain 

 American native grape roots to the phylloxera 

 plant-louse is proving to be the salvation of the 

 grape industry in Europe. Promising efforts are 

 now being made to develop a boll-weevil-resisting 

 variety of cotton. Sojnetimes certain varieties of 

 wheat seem to be resistant to the hessian fly. 



Much can be done around farmhouses to reduce 

 the numbers of house-flies and mosquitos. Put the 

 horse manure in tight sheds so that flies can not 

 breed, or spread it on the fields every two or three 

 days in summer. Drain off or fill in low places 

 where water stands continually or 

 after showers, as such places breed 

 "wigglers" or mosquito larvffi. 



66. Two examples of sucking insects, belonging to the 

 group Juiown to entomologists as the true bugs. 



If the rain-barrel is also screened with wire netting, 

 it will not become the breeding-place of thousands 

 of mosquitos. House-flies may bring to human food 

 the germs of typhoid fever on their feet or mouth- 

 parts, and the only way one can get malaria is 

 through the agency of certain kinds of mosquitos 

 (Anopheles) that may have sucked the diseased blood 

 from some malarial patient, which they then inject 

 into the body of another when they " bite." (Vol. 

 I, p. 297.) 



Spraying and other insecticidal methods. 



For a half century before 1875, the materials 

 used by American farmers to kill insects consisted 

 largely of whale-oil soap, hellebore, lime, tobacco, 

 sulfur and salt. These materials were dusted or 

 sprinkled or syringed on the plants. With the ap- 

 pearance and rapid march of the Colorado potato- 

 beetle across the country from 1860 to 1870, there 



