Are Gnats Attracted to Light?


While there is some variation surrounding what insects constitute as gnats, this article will address only those small flies that are non-biters and are likely to be pests within homes and other structures. This includes fruit flies, fungus gnats, phorid flies and moth flies.

Which Gnats Are Attracted to Light?

In general, the four gnat species listed above are not strongly attracted to light and express very different light-related behaviors.

Generally, fruit flies are not attracted to light and phorid flies are not strongly attracted to light. Moth fly males but not females are attracted to light and may be found around doors and windows.

The one exception to this generality is fungus gnat behavior since both male and female fungus gnats are strongly attracted to light and this behavior is sometimes used to augment other methods of fungus gnat control. Indoors, fungus gnats often show up around windows, doors, TVs, and interior lighting. Outdoors it is common to find them flying around porch lights

Gnat Control

The attractiveness of these gnats to light can be useful for inspecting and monitoring to determine where gnats are breeding and developing. However, lights and light traps are not highly effective for control purposes and are rarely if ever be useful in eliminating a gnat problem. As one might expect, gnat habitat reduction and removal is almost always the best and most effective way to prevent and control gnat populations.

Bug Lights

However, there are numerous reports from residents that keeping outdoor lights turned off, or changing bulbs to low voltage, yellow “bug lights” is helpful when dealing with this problem.

Gnat control product manufacturers have learned that adding a gnat attracting pheromone to a light trap increases effectiveness and can add value to an integrated gnat management program plan.