88 SOME INSECTS INJURIOUS TO TRUCK CROPS. 



to have a very good effect. Just why, is not so clear, possibly because 

 it loosens the ground, breaking up any crust that ma}^ have formed, 

 and allows all the beets to get through at one time and in this way 

 some of them get ahead of the beetles. The farmers think it kills 

 the beetles. Cleaning up hedge-banks and rubbish around the fields 

 has been recommended and appears to have had a good effect. It is 

 a lamentable fact that a field that is slightly weedy when the beets 

 appear will not be mjured as badly as one that is free from weeds, 

 which probably accounts for the fact that replanted beets are rarely 

 destroyed." 



The use of fertilizers. — "N^Hiiere fertilizers are used the plants are 

 undoubtedly aided in recovering from attack by this flea-beatle, but 

 fertilizers are not remedies. Possibly where mineral fertilizers are 

 applied heavily they might have some effect on the larva?, but it is 

 doubtful if a sufficient amount of an irritant salt would remain in 

 the earth to destroy any large percentage of larvae at the time when 

 those which have just developed from the Ggg or have just molted are 

 feeding on the roots. It is worth mentioning, however, that Mr. 

 Theo. Eder noticed that when a fertilizer consisting of 3 jDer cent 

 nitrogen from nitrate of soda, 12 j)er cent potassium oxid (KoO) 

 from muriate (chlorid) of potash, and 9 per cent phosphorus pen- 

 toxid {^2^5) from superphosphates was applied there were prac- 

 tically no flea-beetles. This fertilizer, however, was considered too 

 expensive, owing to the cheapness of hops in the affected region of 

 British Columbia. 



Irrigation. — Irrigation has been suggested and, on the authority 

 of Prof. E. G. Titus, the flea-beetle, when it is working on sugar 

 beets, can be driven away during irrigation by disturbing the beets, 

 thus causing the beetles to jump into the water and be swept away."^ 



Tarred catcliers. — Tarred sheets, boards, or similar contrivances on 

 the plan of " hopperettes," in use against leafhoppers, have been em- 

 ployed in the infested region for capturing the flea-beetles. Mr. 

 Hulbert reports having destroyed large numbers by catching them 

 on tarred sheets as they fell from the vines after being disturbed. 

 Mr. Qua3de also reports success with a " catcher " which he describes 

 substantially as follows: 



The receptacle used consists of a stout canvas about 3 feet by 4, to which is 

 nailed, on the under side, three strips of boards with one at right angles, to 

 keep the canvas taut. A handle is fastened to two of these strips to project 

 upward and backward, by means of which the apparatus is operated. This is 

 lifted from vine to vine and the beetles jarred off with wisps of hay. Usually 

 two men work together on the same row, the two canvases placed together on 

 each side of the vine. 



" Bui. 67, Bur. Ent., U. S. Dept. Agr., p. 112, 1907. 

 66 — VI 



