MEANS OP CONTROLLING INSECTS 



41 



can not wait but must usually resort to artificial 

 insecticides to save his crops. For centuries man 

 has been fighting insect enemies. The Greeks 

 mixed hellebore with milk to kill iiies, and the 



Fig. 59. A hopper-dozer at work in kaflr com. (Kansas Experiment 

 Station Bulletin.) 



Romans required the inhabitants of infested regions 

 to kill certain amounts of grasshoppers. In the 

 middle ages the methods used for the destruction 

 of insects were largely of a spiritual nature ; 

 priests marched around infested fields praying ; 

 anathemas were pronounced over grasshoppers ; 

 or the accused insects were summoned to appear 

 in court and judgment was rendered in the form of 

 an excommunication. Scarcely thirty years ago, 

 two governors of states in America issued procla- 

 mations appointing days of fasting and prayer to 

 stop the ravages of Rocky mountain locusts. It is 

 only within the past quarter of a century that 

 most of the modern scientific methods of control- 

 ling insect pests have been devised. Previously, 

 American farmers resorted to hand-work or to 

 simple mechanical devices, such as bands for 

 canker-worms and codling-moth. The word "in- 

 secticide " was unknown half a century ago, and, 

 according to the dictionaries when man kills an • 

 insect he is an insecticide, he may use an insecti- 

 cide, and he also commits an insecticide. Usually, 

 however, the word is restricted to some material 

 or spray used by man to kill insects. 



We may classify the methods used against insect 

 pests as : international, national, state, local or 

 neighborhood and individual. The first three of 

 these mostly comprise laws or commercial regula- 

 lations, by the enforcement of which attempts are 

 made to prevent the spread of insect pests from 

 one country or state to another, and also to provide 

 for the introduction of beneficial insects. Neigh- 

 borhood and individual efforts usually aim- at the 

 immediate death of the insects either through the 

 enforcement of municipal regulations, by the offer- 

 ing of prizes, by practicing better farm methods, 

 or by the use of insecticidal batteries. 



Laws or regulations are often necessary in 

 insect warfare, but thfey must be supported by 

 public opinion to be effective. Par-reaching and 

 valuable results have been aittained by interna- 



tional efforts in controlling insect pests by quar- 

 antine regulations and by the introduction of bene- 

 ficial insects. Nations can scarcely overdo this 

 kind of control work against injurious insects. 

 Compulsory state legislation to 

 control insect pests will often lack 

 the necessary support of public 

 opinion and hence be difiicult to 

 administer; attempts to annihilate 

 the San Jose scale in Canada by 

 the axe and fire were soon stopped 

 by adverse public opinion. The 

 state inspection laws to prevent 

 the spread of insects by nursery- 

 men have accomplished much good. 

 Local authorities can do much to 

 check the ravages of insects over 

 limited areas by offering prizes or 

 insisting that owners of infested 

 premises shall use certain destruc- 

 tive measures or pay for having 

 the authorities do it. A few neigh- 

 bors can do much to mitigate the 

 ravages of the hessian fly by com- 

 bined action in using early trap strips of wheat 

 and sowing as late as practicable. 



And yet, after all has been said and done by 

 international, national, state or local authorities 

 to stay temporarily the inevitable spread of the 

 world's injurious insect fauna, each individual who 

 raises crops will often find himself face to face 

 with the problem of fighting successfully some 

 insect pest or the loss of his crop. Legislation 

 and inspection or fumigation certificates are then 

 of no avail. Usually his parasitic and predaceous 

 insect friends are also too slow. A nation may profit- 

 ably spend much money to introduce new insect 

 friends; doubtless an extensive national quarantine 

 would keep out some injurious insects for a time, 





Fig. 60. A practicable and effective sticky shield for captur- 

 ing adult grape leaf -hoppers in the spring. 



and the state and local authorities can do much to 

 check the spread of a pest ; but in the end the 

 brunt of the fight will fall on the individual whose 

 crops are attacked. 



