NAVMED P-5010-8 - Navy Medicine - U.S. Navy

8-34 CHAPTER 8. NAVY ENTOMOLOGY AND PEST CONTROL TECHNOLOGY 8-35
j. Control of Eye Gnats (Hippelates
spp.). The eye gnat species, Hippelates pusio
and H. collusor, are the most troublesome to
man within the United States. Efforts to effectively
control these species by the use of aerial
and ground delivered sprays and aerosols have
generally been unsuccessful. Because these flies
commonly breed in fresh turned soil, successful
control can sometimes be accomplished by
modifying agricultural methods. This would
include conversion of cropland to pasture and
shallow disking when cultivation is necessary.
Soil application of insecticides may have some
promise. However, the success of the methods
of agricultural and insecticide control is contingent
on the biology of the flies, but all of the life
cycle information is not yet known. Where eye
gnat problems are encountered and in the
absence of control measures known to be
successful locally, the assistance of appropriate
technical personnel should be obtained.
8-35. Mosquitoes
a. Relation to Man. Mosquitoes rank first
in importance among the insects that transmit
diseases to man. This is partially because their
biting habits vary among genera and species
with regard to habitat, time of day, and host type
and availability. This variability is important
because it causes exposure to and subsequent
transmission of different disease organisms (e.g.,
periodic and non-periodic filariasis). The genera
most frequently associated with disease transmission
are Aedes, Anopheles, and Culex.
Disease organisms vectored by mosquitoes to
man include bacteria (tularemia), arboviruses
(dengue, encephalomyelitis (Eastern, Western,
St. Louis, West Nile, Japanese B, and Russian
Spring-Summer), and Yellow Fever), protozoa
(malaria), and filarial nematodes (Wuchereria
bancrofti, Brugia spp., and Dirofilaria immitis).
Besides serving as disease vectors, many species
of mosquitoes are serious pests of man solely
because of their irritating bites.
b. Biological Characteristics. Mosquitoes
oviposit on the surface of water or on
surfaces subject to flooding. Larvae hatch and
8-38
feed on organic matter in the water, pupate, and
emerge as adults. Mosquitoes use a great variety
of water sources for breeding. These include:
ground pools, water in artificial containers, waterholding
tree holes, and leaf axils. Adult mosquitoes,
when not actively seeking food, rest in
concealed places. Only the females feed on blood.
Depending upon the species involved, the distance
of dispersal from breeding areas varies from
a few meters to many kilometers. Males normally
do not fly long distances from breeding areas;
consequently, any uncommonly large concentration
of males usually indicates that the breeding
area is near.
c. Surveillance of Mosquitoes. See article
8-56 for details on collection.
d. Control. Mosquito control methods are
classified as being either permanent or temporary
depending upon whether they are designed to
eliminate breeding areas or simply to kill the present
population. Aside from the elimination of
artificial water holding containers in campsites,
permanent control measures have a high initial
cost and require considerable periods of time to
complete.
(1) Control of Immature Stages.
Temporary control of mosquito breeding is
accomplished by treating water surfaces with
larvicides. Larviciding equipment is described in
Section VIII of this chapter.
(a) Ground Larviciding. Where no
larval resistance to insecticides has been documented,
solutions, emulsifiable concentrates,
granules, and water-dispersible powders may be
used effectively for larviciding with groundoperated
equipment. The use of granules is
indicated where heavy vegetation covers must be
penetrated or where possible damage to crops
(e.g., rice) is a consideration. Because the percentage
of toxicant and application rate vary with
the type of equipment used, species of mosquito
involved, geographical area considered, and with
the degree of resistance developed, current recommendations
should be obtained from appropriate
technical personnel (see articles 8-4 and 8-5).
9 Nov 2004