54 SOME INSECTS INJURIOUS TO TRUCK CROPS. 
the hops are just coming up and during a season when the hibernated 
beetles are very numerous, in order to get more extensive results. 
BORDEAUX-TOBACCO EXTRACT. 
In endeavoring to combine a deterrent with a contact insecticide, 
the 5-5-50 Bordeaux mixture and blackleaf tobacco extract at the 
rate of 1 gallon to 65 gallons were mixed together. Vines were 
treated the same as in the previous experiment, and on examination 
after five days it was observed that the Bordeaux-tobacco mixture 
was as effective a deterrent as the Bordeaux mixture alone. Its in- 
secticidal properties were tested by spraying a group of beetles which 
was placed upon a soil-covered cloth, and which, after being sprayed, 
was covered with a cage. After twenty-four hours 65 per cent were 
dead. In cases where the beetles are very numerous and a large 
percentage of them are around the vines, a Bordeaux-tobacco mix- 
ture should prove effective. 
TOBACCO DUST. 
In order to determine the value of ground tobacco as an insecti- 
cide, a large sheet was covered with a thin layer of soil, and on this 
was spread a ring of tobacco dust 13 feet wide. A healthy lot of 
beetles was placed in the center of this ring, and the few that managed 
to cross were caught and placed in a cage. Most of the beetles 
perished in the tobacco dust, and those that crossed soon died. After 
the dew had caked the powder, however, all of the beetles which 
were placed in the center of the ring crossed the tobacco unharmed, 
even though some of them carried small pieces of tobacco with them. 
Although the beetles are able to cross the caked tobacco, the insec- 
ticidal properties are not entirely lost, for when broken up and 
sprinkled onto the beetles it killed them as readily as the fresh 
material. 
Application on mangels.—A large plot was selected in an infested 
mangel patch and the tobacco dust thoroughly applied. The fol- 
lowing day only a few beetles were found on this plot, while the 
adjoining rows contained as many as ever. The tobacco dust is more 
effective on mangels than on hops, because the plants are close to 
the ground and can be more readily covered with the powder. 
IMPRACTICAL MEASURES. 
Against beetles in the poles.—Spraying with a distillate or some 
other contact insecticide was suggested as a means of killing the 
beetles in the poles, but the “ fleas” are so far back in the slivers 
and so deep in the rotten portions of the wood that a spray will not 
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