St. Louis encephalitis virus and control of Culex pipiens may be needed. Additionally,
because habitat preferences can vary greatly even between species of the same genus,
efficient control efforts must be based on proper pest identification. A preventive
medicine specialist has to be able to use scientific names of medically important
arthropods when reporting identifications.
c. Similarly, in writing a report the specialist should refer to the "proboscis" of the
adult mosquito rather than to the common name "beak." In respect to usage of scientific
terms for specific structural characteristics, accuracy and clarity are very important.
Common terms such as head, thorax, and abdomen (the three major body segments of
an insect) are acceptable; however, there are some characteristics for which there is a
specific term. For example, only in arachnids are there found appendages called
"pedipalps." This name implies the function of this appendage and there is no other
suitable term to use.
d. As stated before, the ultimate goal is identification of an arthropod to genus
and species. The genus is placed first and the species is second. The first letter of the
genus is capitalized; the first letter of the species is not. Both words are underlined.
Culex quinquefasciatus, for example, identifies one of the mosquitoes that is important
in the transmission of a group of diseases known as arthropod-borne viral
encephalitides.
2-3.
STANDARD IDENTIFICATION KEYS
a. Standard identification keys are universally used to identify arthropods.
These keys consist of a systematic arrangement of drawings and/or a brief description
of specimens. Rather than having to look in a random fashion for a specimen
resembling the one you are seeking to identify, you are able to make a series of choices
that match with your specimen as you work through the key in an orderly manner untiI,
by the process of elimination, you are able to establish the identity of your specimen.
b. Only by becoming famiIiar with a key can you learn to understand the way a
key works. Figure 2-1 shows a pictorial key to classes and orders of adult arthropods of
public health importance. Pictorial keys such as this, uses descriptive statements as
captions to point out distinguishing characteristics in the pictures, but the pictures are
the chief components that provide a means of quick identification. You work through a
pictorial key by process of matching and eliminating. There may be one, two, three, or
more figures in a set with which you can compare your specimen. When you reach the
last figure in a hierarchical sequence, you look at the accompanying caption to identify
your specimen. Assuming you have not made an error in matching, you wiII then have
made a correct identification.
MD0170
2-3