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little or no kill: lettable sulfur, 100 pounds; derris ponder (5 percent 
rotenone), 10 pounds; water, 1,000 gallons. This is the formula found 
effective as a dip for controlling the short-nosed cattle louse. 
D erma cent or variabilis (Say), the American clog tick 
.C. N« Smith, in a typewritten quarterly 'report to the Division of Insects 
Affecting Man and Animals, Bureau of Entomology and Flant Quarantine, United 
States Department of Agriculture, for the period July- September, 1937 „ gave 
the results of tests made at Vineyard Haven,' Mass., on the control of the 
American dog tick. Tests were made with derris as a wash to kill .and repel 
adult ticks on dogs and horses. In general, it ap-ears that a dip made of 2 
to 4 ounces of derris (rotenone 4 percent) to the gallon will kill all flat 
ticks and most of those partially engorged. Treatment of .animals every 5 or 
6 days should be sufficient to prevent engorgement of ticks, as the animals 
are protected for 3 or 4 days, and ticks attached 1 to 3 days ere easily 
killed. No animals were made sick by the dip, as animals' occasionally are by 
breathing derris dust. Although the dip leaves the dog 1 s hair feeling somewhat 
greasy, no objections were made by the owners. 
The United States Department of Agriculture in a Press Release dated 
lA ay 18, 1938, issued information on how to avoid dangerous tick bites.' 
Keeping ti'eks from engorging themselves on the blood of dogs is a projective 
measure. A pair of forceps is all that is needed to' remove ticks from dogs 
if only a few have attached themselves thereto. Dusting every 5 days with 
derris powder is necessary for dogs supporting a large number of ticks. 
Bishopp and Smith (10) in 1938 recommended application of a derris dip to 
dogs to control the American- dog tick, or common wood tick, which is the 
principal vector of the Rocky Mountain spotted fever in the Central and Eastern 
States and is also capable of carrying rabbit fever (tularemia). Derris dip 
is made by mixing 2 ounces of fine derris powder (containing at least 3 
percent rotenone), 1 ounce of neutral soap, and 1 gallon of tepid water. The 
dip may be applied by putting the dog in a tub containing it, or it may be 
brushed in thoroughly. The dip should be allowed to dry on the dog or, if 
necessary, the surplus liouid may be removed with a towel. The dip can be 
kept for at least a week without deteriorating. If the dip cannot be used 
conveniently, derris powder may be applied next to the skin on all infested 
parts. To prevent ticks from engorging, the powder must be applied every 
other day. The persistence of either the dip or the dust depends on the type 
of dog, and the interval between treatments can be determined best by 
experience. Do not permit the powder or dip to get into the eyes. 
These authors ( 11 ) again in 1938 recommended derris for the control of the 
American dog tick. The thorough application of derris as a powder or wash is 
effective in destroying the ticks already attached and in preventing the 
reinfestation of dogs for short periods. Application is easier when the 
powder is used, and ticks that actually come in contact with the derris will 
be killed, but the animals are less thoroughly covered than when the material 
is used as a wash or dip. In addition to giving a more complete treatment at 
