irrigation, in 1952-53. Pastures and grasslands need not be 
irrigated to produce mosquitoes, since in some places sufficient 
rainfall accumulates in low places to produce the pests. Pastures 
and grasslands are better suited for mosquito production than 
other croplands. 
Mosquito and midge problems also arise from water impounded by 
dams. For example, a costly mosquito-control program is necessary 
in the TVA impounded waters. 
In some areas mosquitoes are becoming resistant to DDT and ree 
lated materials, and it is expected that such difficulties will 
increase. 
Besides being pests, mosquitoes also transmit diseases. The 
most important in the West is encephalitis. Malaria has been 
nearly stamped out in the Southern States, but at one time it 
reduced the effectiveness of farmers and prevented the use of 
good agricultural lands. 
Costs of Controlling Losses 
Insects 
In addition to reducing the quantity and quality of crops, live-~ 
stock, and other agricultural products, insects increase the 
costs of production because of the necessity of applying measures 
for their control. Not only the producer, but also-the processor 
or packer, the shipper, the warehouseman, and the ultimate cone 
sumer are affected. Insect control on farms, in households, and 
elsewhere costs about $00,000,000 per year in this country. 
These costs may be grouped under five major categories = (1) 
insecticidal control, (2) cultural and mechmical practices, (3) 
biological control measures, (i) large#scale cooperative control 
programs, and (5) enforcing and conforming to quarantines and 
regulatory measures, 
The control measures required are developed by research cone 
ducted by Federal and State agencies and by industry. The cost 
of this research is not included in the estimates. 
Insecticidal Control. = The annual cost of all insecticides 
used in this country during the period 192-51 is estimated at 
$195,000,000. The cost of applying insecticides, including the 
cost and depreciation of equipment, is about 9); percent of the 
cost of the insecticides, or $180,000,000. Thus the total annual 
cost of controlling insects with insecticides is about $375,000,000, 
The availability of new insecticides, beginning with DDT which 
was released to the public in 1945, has made the estimating of 
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