Editor's Note: The following article appeared on Mike Merchant's blog, "Insects in the City," which can be found at http://insectsinthecity.blogspot.com. The blog offers readers news and commentary about the urban pest management industry and is excerpted here with permission of the author.
For some reason that I have not quite figured out, winter is high season for mysterious bug bites. Post-holiday stress, extended periods spent indoors, dry skin, static electricity, low vitamin D... whatever the cause, the number of calls from folks who cannot produce any actual pest goes up during the winter months.
Calls from office managers to pest control firms are not uncommon at this time of year. This e-mail I received is typical:
"We have had several employees being apparently bitten by an unknown pest. We are unsure of the pest, however, they are feeling a sudden pinprick-like sensation on their skin. These tiny painful jabs feel like insect bites and the outcome is itchy welts that look just like insect bites.
"We have had the area exterminated by professionals and treated the area with [two pesticides]. The pest professionals indicated that they don't believe the problem is a bug or insect issue. We are not sure the problem as it could be an air duct/air quality problem, allergic reaction, etc."
Although one cannot rule out insects or mites as a cause from this description, here were some points to consider:
- Possible arthropod causes include fleas (unlikely, unless someone is bringing a pet to work) and rodent mites. Rodent mites are tiny, eight-legged arthropods that normally live in rodent nests. They often disperse from nest sites to living areas of buildings where they bite people. They usually can be pulled from the skin with a piece of tape at the time of the bite. Controlling rodent mites starts with eliminating the rodent infestation. Mite bites are typically limited to a small area of the office near to the rodent (or bird, in the summer) infestation. Rodent mites are unlikely to bite people over a whole office — that would require one big rodent problem.
- Winter is a time of dry skin and relatively high static electricity, and the number of complaints of "bites" in offices is higher at this time of year. It's conceivable that floating fiberglass or other sharp fibers in air can be attracted to negatively charged legs and arms to cause prickling, though this is just a theory — untested as far as I know.
- It's a known phenomenon that one person's complaint about "bites" is frequently contagious in office settings. Nearly every pest control professional who has been in the business for any length of time has stories about this. The power of suggestion is very real, and can often be dealt with by assuring employees that the matter is being handled and initiating a monitoring program with sticky cards to verify that there is indeed no real insect issue.
- If no insects or mites can be collected, it's most likely that the problem is imagined rather than real. Nonetheless, it can be difficult to convince employees of this and the best course of action is usually to work closely with the pest control company. Shampooing the carpet or installing air humidifiers may also help reduce dryness and static electricity issues in an office setting.
- Skin welts can arise from a number of issues, including skin irritation from fibers, reaction to scratching, allergies, etc. If the welts are minor and disappearing quickly, it suggests that a real insect is probably not involved.
- As a professional you need to communicate honestly and fully with your building manager. If you opt to "shoot blanks," say with water or an air freshener, the manager should be fully informed and agree with the tactic.
Don't allow yourself to be pressured into applying insecticides for pests that you don't believe are present. Do use sticky cards to assure yourself that mites or some other unusual biting pest is not present. Fungus gnats, which are also common this time of year, often can be the trigger that starts office rumors about biting pests; but fungus gnats do not bite and would not cause welts or itching. And please, let's do our part to stamp out the myth of cable mites and paper mites in this generation. There are no such things.
The author has been an entomology specialist for Texas AgriLife Extension since 1989. Contact him via e-mail at firstname.lastname@example.org.