LIFE HISTORY AND CONTROL OF HOP FLEA-BEETLE. 57 
spray and escaped. This material did not hurt the tender vines, but 
the beetles were not killed unless they were completely covered with it. 
Kerosene emulsion. — According to Professor Quayle's experiments 
of 1908, kerosene emulsion ranks next to blackleaf tobacco extract in 
effectiveness against this flea-beetle. 
Whale-oil soap. — Whale-oil soap at the rate of 1 pound to 10 gal- 
lons' of water was applied to hop "fleas" which were attacking 
mangels. When a beetle chanced to become the center of a drop of 
spray it soon died, but a little soap on one side or on its elytron did 
not injure it in the least. 
Resin lye. — The resin-lye spray used at the rate of 1 pound of 
resin to 10 gallons of water was a little more effective than the whale- 
oil soap, but was far from satisfactory. 
Arsenicals. — Although the hop flea-beetle is supposed to be very 
resistant to arsenicals, laboratory experiments proved that a fair per- 
centage may be killed by the use of either arsenate of lead or Paris 
green. For good results the arsenate of lead should be used at the 
rate of 5 pounds to 50 gallons of Avater, and the vines should be kept 
well covered with it, but since the vines grow very rapidly such a 
method becomes too laborious and costly. 
TRAPS. 
Trap foods. — It is evident from the results obtained in the pre- 
ferred food-plant experiments that the best trap food for beetles, 
either on the hops or on the mangels, is the nettle, the tomato for the 
hop and the rhubarb for the mangel coming next. Since the hop is 
preferred to any other plant, and since it comes up at the same time 
as the nettle, the only chance to use a trap food is in the fall after the 
hops are gone. The borders of the fields are the only places where a 
trap crop can possibly be grown, because, when the hops are gathered, 
the pickers would trample down anything that was growing between 
the rows. If the nettles which grow along the fences are thoroughly 
sprayed with arsenate of lead or Paris green about the time that the 
hops are picked a large number of beetles may be killed. 
Trap lights. — The beetles which were brought into the laboratory 
appeared to be quite positively phototropic, and with the hope that 
trap lights might prove successful these Avere tried under field condi- 
tions. A lantern set on a tanglefooted board was placed in an in- 
fested mangel patch. Although the beetles were numerous on the 
mangels all around the light, only a few of them were attracted to 
it. They could be seen crawling around on near-by leaves, but ap- 
parently had no desire to approach the light. The same results were 
obtained with the acetylene light, the increased intensity having no 
effect upon the beetles. 
Trap shelters. — The use of trap shelters to catch the hibernating 
beetles was one of the first control measures which were thought of. 
