THE CONTROL OF INJURIOUS INSECTS 399 



Professor Sanders of Pennsylvania recommends the following 

 poison bait spray against the adults of the onion maggot: 5 grams of 

 sodium arsenite dissolved in a gallon of boiling water into which is 

 thoroughly mixed a pint of molasses. This bait is applied as a coarse 

 spray of large drops once a week across the onion field throughout the 

 summer. 



For cockroaches and ants in kitchens and pantries powdered borax 

 mixed with sweetened chocolate, scattered in the evening about the 

 haunts of the insects, and powdered sodium fluoride, pure or mixed 

 with flour or plaster, applied by means of a dust blower are effective. 



Sponges filled with sugared water attract ants that infest houses, 

 and large numbers can be readily destroyed. 



7. Ditches, Furrows and Trenches 



When fields are threatened with the army worm or grasshoppers, 

 a ditch or deep furrow made in front of the advancing army has had 

 excellent results. The insects falling into the ditch may be destroyed 

 in large numbers. 



8. The Use of Hopperdozers, Etc. 



In the grasshopper-infested regions of the West hopperdozers or 

 hopper-catchers are used to great advantage. Various devices are in 

 use, but they all agree in principle. They are essentially machines 

 for gathering up the grasshoppers as they are drawn across an in- 

 fested field. Attached to each machine is a contrivance for destroying 

 the insects when collected by means of coal-oil, or tanglefoot, or pitch 

 tar. 



Best results are secured by using the dozers when the hoppers 

 are small. If infested fields are gone over frequently the damage 

 will be reduced to a minimum. ^ 



9. Collecting, Digging-out, Jarring, Etc. 



Under this head are collected a number of mechanical methods 

 which the careful farmer and fruit grower employ to good advantage. 

 Sometimes much damage can be averted by the timely picking of the 



