BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 45 
that losses from this pest can be reduced by proper fertilization, crop rotation, 
and early planting. Where an abundance of land is available the noncultiva- 
tion of land for one season will also aid materially in reducing wireworm popu- 
lations. 
The Gulf wireworm (Heteroderes laurentii Guer.) is becoming of greater 
importance each year in the Gulf region and on the Coastal Plain. This wire- 
worm is likely to be more abundant in land that has been tilled year after year 
than in untilled land. 
BEAN AND PEA INSECTS 
The Mexican bean beetle continues to be the most important pest of beans in 
the United States, and while the winter survival for 1934-35 was lower in 
Ohio than it had been for several years, with favorable spring conditions the 
beetle populations built up to the point where the insect caused considerable 
damage. Both field and laboratory tests of many types of insecticides have 
been conducted in Ohio and Virginia. The work with insecticides showed quite 
conclusively that derris powder mixed with water and applied as a spray gave 
exceptionally good control of the bean beetle, both in Ohio and Virginia. Cryo- 
lite also was effective. For some unexplained reason, the dosage of magnesium 
arsenate, that is, 1 pound to 50 gallons of water, which heretofore had been 
effective in the control of the bean beetle has not yielded the same results during 
the past few seasons, and it is now necessary to use 2 pounds of magnesium 
arsenate to 50 gallons of water in order to bring about the same results. This 
high dosage may result in some injury to the bean foliage. 
With the establishment of pea-canning factories in the Northwest, the control 
of the pea weevil has increased in importance. The utilization of a border trap 
crop and the plowing under of these border plantings prior to the time that the 
main plantings blossom have given encouraging results. During the latter part 
of the year this work was expanded to include studies of the weevil in the 
Dayton, Wash., area. 
The pea aphid again caused heavy losses to the pea growers in Wisconsin, New 
York, and Ohio. The investigations this season consisted primarily of field-plot 
tests with several insecticides, and while the results to date are only of a pre- 
liminary nature and cannot be used as a basis for recommendations on pea 
aphid control, the indications are that a derris powder spray may be useful 
against the pea aphid. 
BEET LEAF HOPPER 
In the beet-growing area of southern Idaho the early-season indications 
were that heavy leaf hopper populations could be expected. The early-season 
prospects were borne out by large numbers of leaf hoppers appearing in the 
beet fields late in the spring. In California, studies on the migration of the 
leaf hopper and its desert host plants have been continued. Observations have 
also been continued on the effect of spraying desert hosts and the elimination 
of Russian-thistle on leaf hopper populations. The actual operation of these 
two latter activities was conducted by the sugar companies and the State 
workers. 
An added feature of the leaf hopper work was the outlining of the critical 
breeding areas of the leaf hopper in southern Idaho. This work had for its 
objective the possibility of controlling weeds in the abandoned land and desert 
areas through proper land handling as a means of reducing leaf hopper popu- 
lations. Evidence accumulated indicates that native grasses which are not 
hosts of the leaf hopper will replace the introduced weed hosts in the large 
breeding areas if given an opportunity. Similar studies have been carried <>n 
in Utah and Colorado; however, the areas involved here are much larger than 
in sou'hern Idaho, and consequently the information regarding the critical 
breeding areas of the leaf hopper in these two States has not been as complete 
as for southern Idaho. 
TOBACCO INSECTS 
Derris powder has shown excellent promise as a control for the tobacco flea 
beetle, especially in the seed beds. Similar control has been secured in the 
field, but the cost of such treatments has not been determined. Barium fluosili- 
cate, heretofore reported as useful in the control of flea beetles in the shade- 
grown tobacco areas of Quincy, Fla., has not proved satisfactory (hiring the 
past season, as it may cause considerable injury to the tobacco. plant. Cryolite, 
