CONTROL OF ARTHROPOD-BORNE AND RODENT-BORNE DISEASES
Section I. MOSQUITO-BORNE DISEASES
Mosquitoes are found all over the world. They are responsible for more diseases
in man than any other arthropod. In tropical and subtropical areas, they breed
throughout the year. They appear in tremendous numbers even in the subarctic regions
during the brief summer season. Most of the disease-carrying mosquitoes are found in
the milder climates and in the Tropics. Different types of mosquitoes transmit different
types of diseases. The three most common genuses of mosquitoes that transmit
diseases are Anopheles, Aedes, and Culex. Each genus consists of many species.
a. Life Cycle. Mosquitoes go through four stages during their life cycle--egg,
larva, pupa, and adult (figure 5-1). The time required for mosquitoes to complete their
life cycle varies greatly depending upon their species and the weather conditions. Most
species of medical importance require approximately one to three weeks to complete
the cycle from the egg to the adult. Adult mosquitoes may live from two weeks to
several months, depending upon their species. The larval and pupal stages of all
mosquitoes are passed in water where the larvae, sometimes called wigglers, can be
easily detected and destroyed. Adult male mosquitoes do not suck blood. It is the adult
females who are bloodsuckers and who transmit disease. A person may not be aware
that a mosquito has "bitten" him (penetrated his skin with its needle-like proboscis) until
later when the site of the bite (puncture) begins to itch.
Figure 5-1. Life cycle of the mosquito.