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 may 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 injured 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. — Where 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 larvse at the time when 
those which have just developed from the egg 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 per cent 
nitrogen from nitrate of soda, 12 per cent potassium oxid (K 2 0) 
from muriate (chlorid) of potash, and 9 per cent phosphorus pen- 
toxid (P 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. a 
Tarred catchers. — 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. Quayle 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. 
