Potatoes 
The potato crop in the United States is attacked by a large num 
ber of insects. The more important. ones of widespread occurrence 
are aphids, wireworms, leafhoppers, the Colorado potato beetle, 
flea beetles, and grasshoppers. Those that cause important damage 
in limited areas only are the white-fringed beetles in the South 
and the potato psyllid in the high plains area. Blister beetles, 
plant bugs, stalk borers, and white grubs.are generally distributed, 
but cause important losses only occasionally. Satisfactory control 
measures are available for most of these insects and are widely used. 
Losses have materially decreased since 1916 when DDT became aveilable, 
but in 1953 DDT and parathion failed to control aphids and the 
Colorado potato beetle in some areas. During the period 19)2=5) 
losses to potatoes from insect pests of all kinds averaged about 15 
percent, amounting to $100,583,000 annually. 
Losses to potatoes in Maine, prior to 1916, due to direct. damage 
by four species of aphids were demonstrated in experimental plots 
by increases in yield of 20 to 73 percent in plots treated with 
rotenone or DDT as compared with plots not treated. When DDT came 
into general use in 196, the average yield in Maine increased 
substantially. The per-acre yield for the period 19):6=52 was 05 
bushels as compared with 277 bushels for 1936-5, Therefore, in 
19i2—45 there appears to have been a loss of about 128 bushels per 
acre that has since been eliminated. Losses due to diseases trans- 
mitted by aphids have been discussed in Chapter IV. 
Losses due to wireworms and other soil insects have also decreased 
because of new control measures, but current losses are considerable. 
Decreases in losses have been particularly outstanding in the irri- 
gated lands, where DDT has been so effective in controlling the 
sugar=beet wireworm and the Pacific Coast wireworm. The eastern 
species of wireworms are not controlled by DDT, but chlordane has 
been widely used successfully, and heptachlor, dieldrin, and aldrin 
are giving promising results. 
The potato leafhopper causes hopperburn, a asease found through= 
out the eastern part of the United States, Although DDT is very 
effective, the small inconspicuous leafhoppers may not be recognized, 
and hopperburn is often thought to be a result of hot, dry weather. 
The potato crop in Colorado, Utah, Wyoming, western Nebraska, and 
Montana is subject to outbreaks of the potato psyllid, which is the 
cause of the disease psyllid yellows. The occurrence of outbreaks 
can now be predicted in time to warn growers of the necessity of 
applying control measures. An outbreak in 199 caused the loss of 
about 7,849,000 bushels. This was the only outbreak during the 
period 1942-51, and surveys indicate that the average annual loss 
was 2,390,000 bushels. 
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