(3) Carbamates. The carbamates are organic sulfur compounds. They
are esters of carbamic acid. They are similar to the organophosphate insecticides in
their physiological action, being inhibitors of the enzyme cholinesterase. In general,
they have a shorter residual effect than the organophosphates. As insects continue to
develop resistance to the chlorinated hydrocarbons and the organophosphates, this
group of chemicals will play a role of ever-increasing importance in chemical pest
(a) Carbaryl. Carbaryl (Sevin) is a moderately toxic (LD50 500-850
mg/kg) insecticide which offers good control of mites, ticks, and fleas. It is highly toxic
to bees and should be used with care if they might come in contact with it.
(b) Propoxur. Propoxur (Baygon) is considerably more toxic than
carbaryl; therefore, most military formulations contain only 1 or 2 percent. It is
particularly effective against German cockroaches resistant to diazinon. It is also
effective against ants, spiders, and many other household pests.
(c) Bendiocarb. Bendiocarb (Ficam) is a moderately toxic (LD50 143
mg/kg) insecticide which is effective against cockroaches, crickets, fleas, ticks, ants,
bedbugs, and other pests. This product is odorless and is registered for use in
d. Toxicities of Insecticides. Table 1-1 summarizes the toxicities of the most
common insecticides. In interpreting this table, the following must be kept in mind.
(1) The data are not the result of laboratory tests and are subject to wide
variations. They cannot be considered exact figures, but only relative values for
purposes of comparison.
(2) The test data were obtained from small animals (chiefly white rats) and
cannot, therefore, be directly applied to humans.
a. General. Repellents are chemical compounds used as liquids, creams,
aerosols, or solids to prevent biting or other annoyance by insects or other animal life.
Personal protection from the bites of mosquitoes, biting flies, fleas, ticks, chiggers,
leeches, and other pests may be obtained by the application of repellents to the skin
and/or the clothing.
b. Use of Repellents. As one of several ways the individual may protect
himself in the absence of other pest control operations, the timely use of insect
repellents is extremely important. Frequently, when the threat of disease transmission
is the greatest, only individual protective measures are available.