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16 INSECTS AFFECTING HEALTH OF MAN OR ANIMALS. 
Repellents may cba of various compounds or simple Substance ; 
These have been recommended: Oil of pennyroyal, oil of citronella, 
oil of peepee, or a mixture a oil of citronella, 1 0z.; spirits of 
camphor, 1 oz.; and oil of cedar, 3 02. 
Any of the foregoing pungent aL or spirits, combined in propor- . 
tions of a few drops to the half ounce of vaseline or lanoline, can be 
used with increased effectiveness, since the grease holds the odor in 
suspense, whereas the oil or spirits alone would evaporate in a short 
SUMMARY OF MOSQUITO-CONTROL MEASURES. 
Avoid the bites of mosquitoes as essentially dangerous, especially 
in districts where malaria is known to exist. 
Use nets or bars when the presence of mosquitoes is even sus- 
pected, as the bites of some dangerous kinds attract httle attention ~ 
on account of their comparative pain- — 
lessness. 
Look for the larvee of yellow-fever — 
and dengue (domestic) mosquitoes in — 
water barrels, water jars, and all water- ~ 
containing receptacles. 
Look for the larve of all malaria- | 
carrying mosquitoes in all natural col- — 
lections of water, no matter how small 
and seemingly insignificant. The 
smaller breeding places are often the 
most important. 
Empty, destroy, or screen all recep- 
tacles and drain, oil, or fill the natural © 
ee ee ere Pupa. collections. Cut or clear off tall grass © 
: , and bushes, if at all thick, for 1,000 
feet about camps and settlements if breeding places exist beyond. 
Use crude petroleum on water of active or suspected breeding 
places and see that the surface is evenly covered. 
Use saucer, cup, or dipper in searching the margins of suspected 
spots for larve; they are not readily discovered otherwise. Skim 
rather than scoop. 
Use as repellents oil of pennyroyal, oil of citronella, oil of pepper-— 
mint, or the mixture mentioned above. | 
LICE. 
Pediculus corporis Deg., P. humanus L., Phthirius pubis L. a 
Among the most important pests of Mexico and the border sections 
are the body louse, the head louse, and the crab louse. 5 
The body louse is by far the most important species on account of 
the facility with which it spreads and the difficulty with which it is 
