Know your beetles

In baseball the difference in batting average between a mediocre hitter and an MVP is often just a few percentage points. In pest control the difference between someone who comes across as a skilled professional and someone who is seen as little more than a hired "bug sprayer" is in the details--like being knowledgeable about the unusual pests. If you want to build customer respect and loyalty there is nothing better than knowing your "bugs".

New technicians typically get trained to identify the most "important" or common pests: cockroaches, rats and mice, structural ant pests, fire ants, and termites. But as time goes on, alert technicians should be adding to their repertoire of pests that they can diagnose. Many of these will be occasional invaders, arthropods that usually live outdoors but can invade buildings when the weather conditions are right or when populations are unusually heavy.

This week's odd, occasional pest is the carabid, or ground beetle. Rather than a specific type of insect, this is a general name for a whole family of beetles. Carabids are most often considered beneficial predators, patrolling the ground for caterpillars and other larvae, even occasionally snails. Carabid beetles are quite common and diverse with over 2200 types in North America. Carabids vary in appearance, but are long-legged and have thread-like antennae which arise between the antennae and mandibles. The body is usually shiny, has lengthwise grooves (striae) on the wing covers, and most often the color is black.

Some species of ground beetles emit noxious secretions as a type of self defense. This morning I picked a ground beetle off the floor of my home. After disposing of it, my fingers carried a strong vinegar-like smell. While not irritating in my case, some species produce compounds that can be irritating to human skin.

Occasionally carabids cause more serious problems. Two weeks ago I received a sample of ground beetles (above) burrowing through sealant around the doorway of an office. Behavior like this can be puzzling unless we understand more about the biology of carabid beetles. In this case the behavior is not surprising considering the daily (circadian) behavior of the beetles.

Carabid beetles are nocturnal, being active mostly at night. They are rapid runners and rarely fly except during mating season (we'll return to this point). Like all nocturnal insects, carabids are negatively phototaxic during the day, that is their instinct is to move away from light. So while we're rubbing the sleep out of our eyes and picking up our morning paper, carabids are looking for dark crevices or digging down into the ground to escape daylight. And carabids, with their flimsy looking legs are very good diggers. If you don't believe me, try holding one in your closed hand for a few moments. Their power to squeeze between fingers is amazing.

This morning I received a call about an RV dealership who was having a problem with some sort of "beetle" digging into rubber sealant used around skylights on their campers, "just like a mouse gnawing into a box". These turned out to be scarab beetles, a slightly different critter, but one with the same behavior as carabids. Over the years I've received similar calls from high school track coaches dismayed by beetles boring into rubberized tracks, churches experiencing leaks when ground beetles started boring through the waterproof foam material on the roof, and schools and businesses concerned about all the "bugs" on the floor. In all cases these beetles were caught in an artificial setting at the end of the night, and simply did what comes naturally: they located a soft crevice into which they diligently burrowed to escape the light.

So what can be done? First, it's important to remember that ground beetles normally would have no interest in visiting a car dealership, athletic field or home. But they will show up at these places if attracted by nighttime lighting. Although carabids do not normally fly, and are negatively phototaxic during daylight hours, things change during mating season. For a few days out of the year, each species of carabid beetle becomes an active flier at night. Also, like other nocturnal flying insects (e.g., crickets), lights such as outdoor floodlights, athletic field lights, security lights, even lit windows become very attractive during these flights.

Like crickets, the first step in solving a heavy carabid beetle problem is to reduce or eliminate outdoor lights during these nocturnal flight periods. The good news is that each species of carabid typically has a short flight period--a few days to a week or so. Even reducing or eliminating lights for a week may be long enough to get beyond the flight period for a given beetle. Pesticides are not likely to be an effective solution to these insects because the beetles are exposed for a relatively short time to spray residues and the damage is done quickly.

A more permanent solution for carabid beetles and other nocturnal flying insects is to look at positioning or type of lighting. Lights should not be shined directly on doorways or windows (or in the case of our RV dealer, above valuable vehicles with rubber seals). Some lights are less attractive to insects than others; for example, sodium vapor lights tend to be less attractive to night-flying insects than mercury vapor or halogen bulbs. Also, using lights with proper shielding to prevent light pollution has a side benefit of being less likely to attract insects from long distances.

Even knowing what's bugging your customer may not bring them full satisfaction. In the case of ground beetle "invasions" there's no quick fix apart from turning out the lights. But a quick identification and explanation (or prompt delivery on a promise to find out), you will certainly gain the appreciation and greater respect of your customers.