ee 
FLY CONTROL ON DAIRY CATTLE 
AND IN DAIRY BARNS 
Recent developments have neces- 
sitated changes in recommendations 
for the controlof flies on dairy farms. 
Studies by Federal and State agencies 
have shown that DDT will appear in 
milk of dairy cows treated with this 
insecticide for insect control. It has 
also been found that spraying of dairy 
barns withDDT maycause milk to be- 
come contaminated with small amounts 
of the chemical. During the past few 
years house flies have developed re- 
sistance to DDT, and the insecticide 
has failed to give satisfactory control 
of this insect:in many places. More- 
over, many farmers have relied too 
much on insecticides for controlling 
flies and have neglected sanitary prac- 
tices which must be followed to reduce 
fly breeding. 
For fly control on the cows, meth- 
oxychlor, pyrethrum, and certain or- 
ganic thiocyanate insecticides are now 
recommended. For use in the dairy 
barns and milk processing plants, these 
materials and lindane also may be 
used. However, lindane is not recom- 
mended at present for application to 
dairy cows for fly control. 
DDT is still recommended for fly 
control ofbeefanimals; and other new 
insecticides, including methoxychlor, 
TDE, and toxaphene, may too be used 
for this purpose. DDT is also still 
recommended for fly control in barns 
iB 
GPO—ENT 489 
