Insect Identification for the PMP: Nuisance or Necessity?

A colleague once asked the great British geneticist J. B. S. Haldane, “Mr. Haldane, knowing what you do about nature, what can you tell me about God?” Haldane thought for a moment and finally replied, “He has an inordinate fondness for beetles.”  Haldane was right. At least 40 percent (400,000 species) of all described insect species are beetles.

Insects and other arthropods occur in nearly every habitat on earth. They make up more than 75 percent of known animal species and they far outnumber all other forms of visible life. Worldwide, more than one million species have been identified, yet entomologists estimate the total number of species at 4 to 30 million.  Incredibly, it is likely that more than 75 percent of all insect species remain undiscovered!

ROLE IN IPM. In the ninth edition of the Mallis Handbook of Pest Control, Dr. Richard Kramer wrote, “Simply stated, pest management is problem solving. It involves the collection of information, analysis of the data and development of a strategy to resolve the pest problem.” This statement suggests that pest management is a decision-making process, and that the quality and efficacy of a pest management program is directly related to the quality of information available. How is this information obtained?  By inspection, of course! The quality of information is related to the thoroughness of the inspection, and one valuable piece of information that must be determined is the identification of the offending pest.

Why should pest management professionals invest the time to accurately identify a pest?  Insect identification initiates a decision sequence that leads to successful pest control (for correct identifications) or, in some cases, flawed decision-making leading to recurring problems (for incorrect identifications). If we can properly identify a pest then we can learn more about its biology – for example what it eats, where it lives, what conditions favor its presence, etc.

Without this information, decisions regarding Kramer’s “strategy to resolve the pest problem” are guesses. If the pest identification is incorrect (or not performed) then decisions, however well-intentioned, regarding management of the pest may be flawed.

Incorrect identifications are usually not costly, but in some cases they can result in poor control or callbacks. Correct pest ID can therefore mean the difference between controlling and not controlling a pest problem. A few examples illustrate some of the potential consequences of misidentification. In case #1, a lucrative account was nearly lost. In case #2, misidentification nearly led to an unneeded structural fumigation.

• Case 1: A PMP was struggling to eliminate an ant infestation in the intensive care unit of a hospital, and was close to losing the account. Having read that Pharaoh ants can be an important pest in hospitals, the PMP concluded that Pharaoh ants were the problem. The ants were actually Argentine ants. The PMP’s initial corrective action (indoor baiting) was appropriate for Pharaoh ant control, but not for Argentine ants which mainly nest outdoors. Correct species identification led to the development of an effective control plan, focused on outdoor breeding sites.

• Case 2: A PMP, representing a homeowner wanting a second opinion on an insect ID, submitted a brownish-black beetle for identification. The first company contacted identified the specimen as a Lyctid powderpost beetle, and they were planning to fumigate the structure. The insect was actually a red flour beetle, a common stored product pest. It superficially (size and color) resembles a Lyctid beetle but belongs to a different family of beetles. Most importantly, red flour beetles do not eat wood. Had the homeowner not requested a second opinion, what might have been the outcome of this case?                                                                                                                                                      

COMMON LAB SUBMISSIONS. Identification of arthropod samples submitted by Georgia homeowners and St. Louis PMPs are summarized in Table 1. Not surprisingly, beetles, bees and wasps, and flies dominate the list. In both datasets, drugstore beetle adults (Figure 1A) and dermestid beetle larvae (e.g., carpet beetles, Figure 1B) were the most common submissions. Fruit flies and midges were the most commonly-submitted flies. A variety of spiders were submitted for identification but the main concern was usually not a taxonomic determination but rather an assurance that the spider was not the poisonous brown recluse spider.

COMMON LAB SUBMISSIONS. Identification of arthropod samples submitted by Georgia homeowners and St. Louis PMPs are summarized in Table 1. Not surprisingly, beetles, bees and wasps, and flies dominate the list. In both datasets, drugstore beetle adults (Figure 1A) and dermestid beetle larvae (e.g., carpet beetles, Figure 1B) were the most common submissions. Fruit flies and midges were the most commonly-submitted flies. A variety of spiders were submitted for identification but the main concern was usually not a taxonomic determination but rather an assurance that the spider was not the poisonous brown recluse spider.

Table 1.  Arthropod identifications made by the Georgia Homeowner Insect and Weed Diagnostics Clinic from 2002-2006 (mostly homeowner submissions) and in St. Louis, MO from 2005-2008 (PMP submissions).
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                                                                                                                                                                                                                                                                                                                  Group       Georgia  St. Louis
                                                                     (% of total)   (% of total)
__________________________________________________________________________
Coleoptera (beetles)                                         22%             25% 
Diptera (flies)                                                   11%             17%
Collembola (springtails)                                     ---               11%
Spiders                                                            10%              9%
Delusory (no pest detected in sample)               ---                6%
Psocoptera (booklice)                                      ---                4%
Hymenoptera (ants, bees, wasps)                     18%             4%
Lepidoptera (butterflies/moths)                         10%             2%
Homoptera (aphids, whiteflies, etc)                  <8%             1%
Hemiptera (true bugs)                                      <8%             4%
Isoptera (termites)                                            <8%            1%
Other IDs                                                         12%            16%
________________________________________________________________________
Total # IDs                                                       1,484          143

Springtails (Collembola) and booklice (Psocoptera) deserve special mention. Both Orders contain small (0.7 - 3 mm), soft-bodied insects that can be difficult to see, let alone identify. Springtails are wingless and feed on decaying leaf litter, plant materials, bacteria and fungi. Although usually associated with damp conditions, population outbreaks involving thousands of individuals can also occur during periods of abnormally dry weather. Occasionally, springtails, which are most commonly found in mulch or thatch, may show up in bathtubs and sinks, where they likely originate from damp, overflow drains or areas where moisture has been trapped behind a showerhead or drain. Booklice are omnivorous and will feed on almost any stored product of plant or animal origin as well as molds and glue.  Booklice can also show up in new homes, where populations flourish from the damp conditions brought about by building with wet or “green” lumber. They are often found in damp (but usually not wet) situations where they can reach extremely high population densities under favorable conditions. Both springtails and booklice are species whose presence generally indicates excessively damp conditions.

HOW TO GET YOUR PEST IDENTIFIED. Because most PMPs are not entomologists and few have direct access to a company technical director or other specialist, it is important that they have knowledge of how to identify insects. For this reason, we have compiled several suggested resources that PMPs can use to help get an arthropod pest identified:

 Purchase a collection of reference books on urban insect pest identification. Examples include the NPMA Field Guide to Structural Pests (by Eric Smith and Richard Whitman) and the PCT Field Guide Series. These guides contain good photos and basic information on pest biology.

 Locate, and take advantage of, insect identification experts in your area. These individuals may work for local, state or federal government agencies (regulatory or other agencies), they may be entomologists associated with a college or university, employed by a manufacturer or distributor, or perhaps a technical director within your own company. If you live in a state with a county-based extension service, get to know your county extension agent. A well-connected county agent can be your key to a diversity of insect identification experts at your state land-grant university.

 Learn how to search the Internet for insect identification resources, illustrations, and photographic images. Take advantage of insect identification, as well as other training materials, available on University Entomology Department websites.

 Make, and maintain, a reference collection of local pests for technicians to consult. Not only is an insect collection valuable for training, but when seen by the general public (your clients) it promotes a professional image of your company. Ultimately, make it a goal for every technician to be able to sight identify at least 50 of the most common urban pest insects in your area. Insect collecting and storage equipment can be obtained from BioQuip Products (www.BioQuip.com; Phone 310- 667-8800).

 Invest in a good binocular microscope to aid in the identification of pests. Most of the difficult-to-identity arthropod groups are small, and identification can be difficult without sufficient magnification.

SUMMARY. A critical component of pest management programs is the correct identification of the offending arthropod pest. Correct pest identifications lead to information on the biology of pests that aids in the development of pest-specific action plans. The act of pest identification has a definite purpose, and in some cases can mean the difference between solving and not solving a pest problem. Of more than 1,600 samples submitted to insect identification labs in Georgia and Missouri, the greatest percentages were beetles, flies, bees, and wasps. In Georgia and St. Louis, spider identification was generally less important than knowing if the specimen was a Brown Recluse spider. More than 95% of spider samples were not Brown Recluse. Because accurate pest identification is so important to the development of technically-sound action plans, we list several resources for use by PMPs to aid them in identifying pests.

Steven R. Sims, Ph.D., is Senior Research Entomologist at Whitmire Micro-Gen and can be reached at steve.sims@wmmg.com, and Daniel R. Suiter, Ph.D., is Associate Professor of Urban Entomology at the University of Georgia Griffin Campus and can be reached at dsuiter@griffin.uga.edu (www.gabugs.uga.edu). Lisa M. Ames, M.S., directs the University of Georgia’s Homeowner Insect and Weed Diagnostics Clinic, and can be reached at lames@uga.edu.