THE WAR ON INSECTS 299 



we need a great variety of machinery for applying pow- 

 ders and liquids, and such machinery is now obtainable 

 almost throughout the civilized world, to meet the needs 

 of the man who wishes to protect one plant as well as of 

 him who farms ten thousand acres. There is every 

 range from the little atomizer to the steam pump, and 

 from the little powder bellows to the rotary fan blower 

 capable of enveloping a large tree in a dust cloud. Spe- 

 cific description of such machinery would be of little 

 avail, and he who has the selection need keep in mind 

 only a few fundamental points. The apparatus should 

 be so simple as to be fully understood by the pur- 

 chaser; it should be well made and of the most durable 

 material; it should be more than equal to the utmost 

 demands ever made on it; it should be able to give 

 great force to the material issuing from spout or nozzle, 

 and there should be a nozzle or spout capable of bring- 

 ing the dust or liquid into actual contact with all the 

 insects to be reached, under all the circumstances 

 under which they occur. Thoroughness of application 

 is always essential to success, and careless work is al- 

 ways wasteful and expensive work. 



We are not confined in our work to insecticides 

 merely. Modifications of the primitive method of col- 

 lecting potato beetles in tin pans with a scum of kero- 

 sene are still in use, and in some cases form our only 

 practical line of offense. Leaf-hoppers and grass- 

 hoppers are collected by means of hopper-dozers drawn 

 by man or horse power over infested fields, gathering 

 up the insects on a bed of soft tar or petroleum. We 

 have similar contrivances to run under grape vines 

 into which we jar rose-chafers, and wheeled, umbrella- 

 like structures to capture plum curculios. In a few 

 cases when large, conspicuous caterpillars like those of 

 the hawk-moths infest low plants like tobacco or toma- 



