Gnat Traps

GENERAL INFORMATION

A myriad of fly traps are sold in home improvement stores and online. In many cases, users of these traps provide a rating that provides an overall summary of the trap that may or may not accurately assess the trap’s ease of use or ability to trap gnats. Therefore, always request information about fly traps from your pest management professional before making a purchase.

Gnat traps may be useful if you want to find out where gnats are developing and what kind of gnats are problematic. However, homeowners often purchase traps hoping the traps will eliminate gnats. That notion rarely works out since both homemade and commercially available traps only catch the gnats that are visible, but do not effectively reduce or eliminate the gnat’s developmental sites and conditions that are producing gnats.

For example, to eliminate fruit flies, the homeowner must locate and eliminate their breeding and development sources in drains, garbage containers, decaying fruits and other sources of moist decaying organic matter. Removing these sources removes the fruit fly problem. Trapping or otherwise killing only adult fruit flies may temporarily reduce, but not solve the problem. In other words, gnat traps can be good monitoring tools that will let you know where gnats are most active and plentiful, but are rarely good control and management tools.

Rather than buying expensive traps, the better way to approach gnat control is to contact your pest management professional (PMP), request an inspection and use his or her experience, skill and knowledge of the target pest to prepare a comprehensive fly management plan. In addition, your PMP will provide advice about gnat traps you may be interested in purchasing.

TYPES OF TRAPS THAT ATTRACT GNATS:

HOMEMADE GNAT TRAPS

The internet provides lots of information about materials and methods that enable homeowners to make their own gnat traps. Some examples include:

  • Using a solution of vinegar, wine, decaying fruit or beer placed in the bottom of a jar that has a paper cone placed over the top of the jar to prevent the trapped flies from escaping. There are many commercially designed container traps that are more refined in their appearance, but function in the same manner as the jar trap.
  • Place a piece of duct tape or clear tape over a sink drain you suspect may be the development site for drain flies. Leave a small portion of the drain uncovered since the flies will respond to the available light and move upward to the drain opening. Leave the tape in place overnight with a room light on and inspect the tape in the morning.
  • Since drain flies may develop in walls or floors where a pipe is leaking, cut a hole in the wall or floor (you may want a home handyman to do this) and place a clear plastic cup or sticky insect trap over the hole. Adult flies in the wall or under the floor will fly to light, get caught in the cup and you’ve identified a drain fly source.

SIMPLE COMMERCIAL ADHESIVE TRAPS

These traps are designed to be used either with or without pheromones.  Pheromones are chemical compounds that many insects use to locate sources of food, developmental sites, as well as mates for reproduction.  For information regarding the effectiveness of gnat pheromone products and pheromone and non-pheromone traps, consult your PMP.

  • The simplest adhesive trap is the old fashioned fly strip designed to be unrolled and hung in an area where flies are a problem. These sticky strips will catch gnats, but only by coincidence.  However, they might be useful to help identify an area where gnats are developing or accumulating.
  • Use of a commercially manufactured fruit fly lure or other gnat lure placed on top of a sticky glueboard or trap may be a good gnat trap.
  • Use of a commercial sticky board that can be placed in a houseplant pot can capture fungus gnats that might be originating from the plant.
  • Use of cardboard tubes that range from 1-3 feet long that are covered with adhesive and fly pheromones.

COMMERCIAL ELECTRIC TRAPS

Commercially designed electrical fly traps are generally used in restaurants and other business establishments rather than the typical residence.  The primary use of these traps is to capture larger flies such as house flies using either an electronic grid (zapper) or an adhesive glueboard that traps flies that are attracted to a source of light contained within the trap.  Using electrical fly traps is very effective and is an important component of food service and warehouse house fly management programs.   An important advantage of these traps is they are on the job 24 hours a day.  However, they do require some maintenance and, over time, the light bulbs do lose their attractiveness and must be changed.  Information about manufacturers and various types of electrical fly traps is readily available from your PMP.

These kinds of light traps do attract some fruit flies, male phorid flies, moth flies and fungus gnats and are useful to help discover areas where gnats are developing.  However, these traps will rarely be useful to reduce or eliminate a gnat problem since habitat remediation is necessary to prevent and control gnat populations.