458 



J.V ECONOMIC ENTOMOLOGY. 



disturbs the proportion of oil and water, and the results are seen 

 in injury to trees and lack of effect on insects. 



Practically, then, the whole matter of selecting- an outfit for 

 applying insecticides from the wide range of those on the market 

 is on exacdy the same plane as the selection of any other bit of 

 farm machinery. The lowest priced machine is not always the 

 cheapest, nor is the highest priced always the best — simplicity 

 rmd durability at a moderate cost should be aimed at. 



.Special apparatus for a special purpose is occasionally proposed, 

 placed upon the market, and then abandoned. Such was the 

 McGowen injector for applying bisulphide of carbon to under- 

 ground insects. The instrument was fully adapted to its purpose, 

 but the demand was not sufihcient to warrant its continued manu- 

 facture. 



So, local needs develop collectors for definite purposes; like 

 " hopper-dozers" for gathering grasshoppers or leaf-hoppers ; or 



Fig. 474. 



" Hopper-dozer" for man-power. 



"curcuHo catchers " for collecting the pestiferous plum curculio ; 

 or fans or other machinery for gathering grape-leaf hoppers, etc., 

 etc. Such special devices are usually brought to the notice of 

 those that need them through the agency of the experiment 

 stations ; their detailed description would enlarge this chapter 

 out of all due bounds. 



Finally, a few words as to fumigating outfits. Since the advent 

 of the San Jose or pernicious scale in the Eastern and Central 

 States, and the general adoption of the hydrocyanic acid gas 

 treatment for nursery stock, so many kinds of boxes, tents, and 

 other coverings have been described that even the mere enumera- 

 tion would make quite a page. Briefly stated, the requisites for 

 successful fumigation are a tight covering and pure chemicals. 



