LEAVE THE LIGHT ON

As urban centers expand into rural markets, a variety of problems begin to impact people and businesses — and some of the biggest problems are flying insects. Typically, PCOs tend to include only filth flies when considering flying insect control, but there is a plethora of other insect pests that can cause problems in suburban areas.

Depending on the region of the country, flying insects that may enter structures include termites, grasshoppers, flies, bees, wasps, ants, leaf hoppers, butterflies and moths, among many others. Any of these insects flying around in a hospital, restaurant or food-handling facility could cause contamination, code violations and other types of trouble.

FLIGHT NAVIGATION IN INSECTS. Insects, as a group, evolved to their present forms millions of years before humans. Whenever considering insect behavior it is often helpful to ask, "What were these insects doing before people?" Of course, there are a few insect species that have adapted to reliance on man (i.e., German cockroaches and human parasites), but what we typically interpret as activity focused on man is actually just the insect doing what comes natural in an unnatural situation.

Night-flying insects typically orient their flight paths to the moon, normally the brightest light in the night sky. In flight, the insect tries to maintain a relatively constant angle to the moon, which appears to be stationary and, more important, unattainable. A candle, lamp or other man-made light source throws the insect’s navigational system out of whack.

Insects are "hard-wired" into nature. A sky with multiple light sources is un-navigable to an insect. When an insect goes near a light source, then that becomes the brightest navigational aid, drawing the insect in to eventual death. When the landscape is relatively dark, as in rural areas, a single point of light may draw insect species from miles away.

Day-flying insects are capable of seeing light in the ultraviolet (UV) portion of the light spectrum and orient to its source. Because few light sources are as brilliant as the sun, other sources of light do not typically affect insects’ behavior (see related story on page 36). When the insects are trapped indoors, they are attracted to windows and other light sources. On occasion, day-flying insects are attracted to lights at night because the visual cues disorient their behavior.

LIGHT TRAP SELECTION. Most PCOs have been asked about "bug zappers" at some point in their careers. Bug zappers use UV light and attract only a few mosquitoes because the bulb and transformer of the trap generate a heat source. They do attract flies, moths, stinging insects and other flying insects. The best advice for people asking this question is for them to buy the biggest bug zapper they find and give it to their neighbor. This will pull the insects off of their property.

Any experienced PCO has found clients using bug zappers indoors, with or without catch-pans. If these traps were installed in any sort of food-handling establishment, then those establishments were in violation of product-use instructions. This is because when an insect hits the electrocution grid in the trap, it may explode, scattering a portion of the remains as a shower of particulate contaminants. When used in a food-handling facility, they must be fitted with a hopper-type catch pan and not be installed over or adjacent to a food-preparation, -processing or -storage area.

The biggest questions to ask when setting up a light trap program are: "What is the goal?" and "What are the insects involved?" Light traps may be used outdoors to capture flying insects that are a nuisance, such as certain courtyard and loading dock situations. They may be used indoors to intercept flying insects as they enter a building or facility or to harvest any flying insects that may infiltrate into critical areas, such as an operating suite or a restaurant dining room. Light traps may also be used to monitor for insect problems that originate internally, such as stored product pests, textile pests and several species of flies.

Light traps can be grouped into three types: hanging traps, wall-mounted units and wall sconce traps. Hanging traps can be divided into the professional "zapping" type and the non-zapping type. For the pest control industry, the non-zapping types usually include a glueboard trapping surface, although there are specialty traps, generally used by entomologists, that employ a live catch mechanism employing funnels, baffles and/or fans.

Wall-mounted traps may also include zappers and non-zappers, which usually include a type of sticky harvesting surface. Some wall-mounted traps contain active trapping devices, such as a low-voltage grid, that stuns insects, causing them to fall into the glue. But most are passive, relying on behavior or reflective surfaces to get the insects into the glue.

Wall sconce traps are light traps made to resemble wall-mounted lamps or clocks and use reflected or diffused light to camouflage the trap in a highly visible area. How well the light is reflected determines how attractive these traps are to flying insects.

Recently, I observed wall sconce traps mounted to black felt walls. Virtually no light was reflected and consequently trap catches were zero. It probably should be mentioned here that trap catches should be analyzed and counted on a regular basis. The types of insects captured can provide a wealth of information about facility operations and potential problems. Capturing night-flying insects in the center of a building may indicate that a pallet of goods, delivered at night, sits on a dock under a light before it is transported through the facility. Those same insects in a commercial kitchen may indicate that a door is being braced open at night for a period of time during smoke breaks or trash removal.

LIGHT TRAP PLACEMENT. I once had a client take delivery on a light trap and complain to me that it wasn’t working and that it should be removed. Upon investigation, I found that it wasn’t plugged in. Light traps should never be delivered to clients; they should be installed by trained professionals. Nothing is more frustrating than visiting a client month after month and finding one or more new light traps still sitting in the box. Once installed, trap maintenance should be included in the service program and PCOs should make sure they are kept clean and effective.

When laying out the placement of light traps, start with a diagram of the facility (visit www.pctonline.com for an example). Ideally, the diagram should include notations about the building’s neighbors (are they adjacent to a slaughter house?). Prevailing winds should also be indicated since they will make a difference on the types of insects captured. Consider the landscaping as a source of flying insects and record the location and type of outdoor lighting on the map. These lights will draw insects to the building, often right to the doorways.

When light trap placements are made, none of the traps should be visible from the exterior of the building to keep from drawing additional insects to and into the facility. Ideally, light traps should be placed on the inside, close to each outside door and opening window. These traps are positioned to intercept and capture flying insects after they have entered the building. This is the first line of defense. The second line should be in the people/product traffic areas, where these outdoor interception zones are met. These capture infiltrators and hitchhikers that the first line traps miss. Finally, traps should be installed in critical areas that have a zero or near zero tolerance of flying insects, such as operating rooms, dining rooms, "clean rooms," and food- preparation areas.

As a general rule, light traps should be placed as low as possible (ideally 4 to 6 feet off the ground) since this is where many of the target insects spend time. This usually isn’t practical since people tend to pile things to eye level, blocking a low-installed light trap from much of the area to be covered. Usually, to maximize the line-of-sight coverage of a light trap, they must be installed at 6 to 7 feet. Finally, take into account competing light sources when installing light traps. Placing a trap in a poorly lighted area will be far more effective than placing a trap on a windowsill. Make sure that the power source used is continuous and doesn’t get turned off at night. Too often, this is the cause for trap failure. Whenever possible, light traps should be hard-wired into the building or have dedicated outlets.

CONCLUSION. Light traps, by definition, are IPM devices and provide PCOs opportunities to illustrate professionalism and expertise. Light trap manufacturers and suppliers to our industry are eager to train a professional on selection, placement and installation to maximize the effectiveness of their products. Take full advantage of them.

Standard incandescent and fluorescent lighting have little or no effect on professional flytrap performance, as long these lights are not placed where they draw additional insects inside, according to the Gilbert Industries Web site, www.gilbertinc.com.

The author is president of American Environmental Services Inc. in Tucson, Ariz. He can be reached at dseemann@pctonline.com.