The second phase of an insect control program involves the use of chemicals.
Various insecticides are available and these products can be classified into two groups:
sprays and fumigants.
a. Residual sprays are applied to walls, floors, and around cracks and crevices
or anywhere insects may gain access to a building. Among the most common residual
sprays used by the military are sodium fluoride, chlordane, diazinon, lindane, and
dieldrin. All of the above except sodium fluoride and diazinon are chlorinated
hydrocarbons. Diazinon is an organophosphate and sodium fluoride is a fluorine
b. Residual spray compounds are, as the term indicates, persistent. The main
advantage is that insect kills are accomplished for some time after the actual
application. Some of the compounds, however, are more persistent than others; and
dieldrin is so persistent that some hazard to other animal populations occurs by virtue of
the fact that foods consumed by these animals may have relatively high concentrations
of the compound remaining on them. The other compounds listed with dieldrin may
also be highly toxic and residual in nature, depending on their formulation. Also, the
other toxic residual sprays are more specific to certain insects.
c. Another spray used as an insecticide is termed a space spray. These
compounds are less toxic and do not exhibit residual effects. They are only effective
against insects not already in a product or its container. They are applied as aerosols
and are commonly used when excessive infestations are not apparent. The two
compounds most commonly used by the military are malathion and pyrethrum.
Malathion is an organophosphate and pyrethrum is from a class called pyrethrins.
d. All of the compounds discussed previously have toxic effects on the nervous
system of insects and other animals as well. It is of utmost importance that the least
toxic and minimum amount of compounds be used that will accomplish the eradication
of the infestation problem at hand. Many of the insecticides can be more or less toxic
and residual, depending on how they are formulated and applied. Some can be used
both as residual sprays and space sprays.
e. Fumigant chemicals are also used frequently by the military as an effective
procedure for elimination of insect infestations. In one instance, a fumigant is used as a
preventive measure to avoid the possibility of infestations. Fumigants are different from
ordinary insecticides due to their penetrative ability. Often times, fumigants are used in
grain storage areas because the fumigant gas can penetrate several feet into the grain.
Fumigants yield excellent destructive results of insects around and within containers of
subsistence. Fumigants are potentially dangerous to humans as well as any other
animal; therefore, trained personnel only may use fumigants. There are two fumigants