LESSON 2
ARTHROPOD IDENTIFICATION
2-1.
GENERAL
a. As a preventive medicine specialist, you may someday be asked to
recommend a method for controlIing a certain type of arthropod. This request could
come from a dining facility manager who has found "bugs" in his dining faciIity; or, it
could come from a high level staff officer who is responsible for planning a field training
exercise in an area that is known to abound with many different types of arthropods.
There are many ways in which you may become involved with arthropods. The end
result wiII usually be that of `recommending control measures for these arthropods or
actually performing the control operation yourself.
b. Before any sound recommendations for control can be made, it is imperative
that the arthropods involved be identified. The science of classification is known as
taxonomy. The ultimate goal is to identify an arthropod specimen down to its genus and
species. Trained specialists are able to identify to genus and species those arthropods
that are important in transmitting disease. They do so by the same method that wiII be
taught in this lesson. That method employs standard identification keys. These keys
have been developed, after years of research and study, by entomologists to classify
the arthropods into meaningful groups. One of your jobs as a preventive medicine
specialist wiII be to use these keys to identify arthropod specimens.
2-2.
USE OF CORRECT SCIENTIFIC TERMINOLOGY
a. It is important to use the scientific names of genus and species when referring
to a particular arthropod. A species is a group of individuals that are all very similar in
appearance and habits, and that naturally mate within their own kind but not with
members of other species. The genus and species stays the same for a particular kind
of insect regardless of where in the world it occurs or in which language it is written.
However, common names often are different between countries and even in different
parts of the same country. Ixodes dammini is the same species whether it is in the US
or in Germany. This information could be important to a preventive medicine specialist
whether serving overseas or in the US.
b. It is imperative that arthropods of medical importance be correctly identified
before any control recommendations are made. In many situations without identification
to the appropriate level, control action cannot be implemented. As an example, both
Culex pipiens, which is the primary vector of St. Louis encephalitis, and Culex tarsalis,
which is a primary vector of western equine encephalitis, occur in the central US. It is
obvious that identification only to Culex is not sufficient information. If a preventive
medicine specialist is doing a survey of mosquitoes in this area and identifies Culex
pipiens as a species, which is increasing in abundance, then he knows under these
circumstances that there is an increase in the risk of people being infected with
MD0170
2-2