NOTES ON INSECT IDENTIFICATION, BIOMONITORING
AND MY IDENTIFICATION MANUALS
(last update 16 December 2002)
Biomonitoring of aquatic ecosystems involves the study of the diversity of the organisms that inhabit those systems. The most abundant aquatic organisms found in most freshwater systems are usually insects. Some insects are indicative of certain environmental conditions, and can be considered similar to canaries in mine shafts, in that if the canary no longer functions, something must be wrong! Thus, a study of the insect fauna of streams, lakes and other aquatic systems may inform us of the condition of that water body. However, although they are easily found and collected, aquatic insects are not as easily identified at the species level. Because some species in the same genus may have different tolerances or environmental requirements, identification should be made to the species level. Measures of the biodiversity of a system are only meaningful when done at the species level.
There are several reasons why insect identification is difficult:
1 - There are so many of them!! There are millions of insect species, many of which are still new to science and have not been named.
2 - Many biologists have inadequate training in entomology (the study of insects).
3 - Much of the literature on insects is out-of-date, incorrect, hard to access or so technically complicated that only a specialist can understand it.
Why is correct identification of specimens important?
1 - Many species are restricted to certain habitats or environmental conditions; these species can be excellent indicators of various kinds of pollution, or the absence of pollution. Incorrect identification may lead to a misunderstanding of environmental conditions.
2 - Long-term studies must have a reliable base from which to work. If a species is identified incorrectly during a study, and is later identified as a "different" species, comparisons of past, present and future populations at the same site and between sites would be impaired.
With the exception of the water beetles (Coleoptera) and the aquatic bugs (Hemiptera), in which both larvae and adults live in the water, the majority of insects found in freshwater are the immature stages of winged adults. Most insect species are based on characters found in the adult stage. Many immature insects are not yet associated with their adult stage, and many undescribed species occur. Thus, identification of many of the immature forms found in freshwater is difficult, if not impossible. However, many advances have been made, and accurate identifications are feasible if biologists are properly trained, have access to up-to-date literature and a reference collection, and have their identifications verified by an expert.
In terms of numbers of species, the two largest groups of freshwater insects are the chironomid midges and the water beetles, each with over 300 species occurring in Florida. Chironomid midges are often the most abundant organisms, in terms of number of species and numbers of individuals, in many freshwater habitats. Dr. John H. Epler has produced identification manuals for both of these very difficult groups that should make their identification much easier. Utilizing a format developed by Dr. Epler, these manuals are the most up-to-date tools available for the identification of these two groups in the Southeast US. Both feature concisely written, unambiguous dichotomous keys that are accompanied by numerous illustrations next to the key couplets, and contain diagnoses (short, concise summaries of the characters that distinguish the organism from its closest relatives), references to pertinent literature, notes on distribution and additional information to aid in identification. Much of the technical jargon associated with insect taxonomy has been translated into terms more readily understood by most biologists with minimal entomological training. Click here for the latest information on how to obtain them: Identification Manuals
IN ORDER FOR A BIOMONITORING PROGRAM TO WORK: