Flight interception trap

Flight Interception Trap

The Flight Interception Trap or FIT is a widely used trapping system for flying insects. It is especially well-suited for collecting beetles, since these animals usually drop themselves after flying into an object, rather than flying upward (in which case a malaise trap is a better option).

The basis of any Flight Interception Trap consists of an upright placed see-through barrier under which one or more small basins are placed. The barrier may consist of such materials as plastic mesh, a transparent plastic sheet or even plexiglass. The basins are filled with a preserving fluid such as ethanol, propylene glycol or salt-saturated water. A small amount of detergent is added to break the surface tension, causing the insects to sink.

The location of the trap is important to maximize results. Depending on the desired species the construction can be put in open land or in the forest. It is important to place the barrier in a straight angle with the most likely flying route for insects (e.g. blocking a forest corridor).

The basins can be checked daily (when it is e.g. important to check the activity of the desired insects under different weather conditions), weekly or even less often. Maximum time between two checks depends on the used preservatives, since not all preservatives are equally suited for preserving insects for a longer time.

To prevent the basins from filling up with litter most researchers place some kind of roof over the trap. This keeps leaves from falling in while it also keeps the rain out (which could otherwise dilute the preservative or cause an overflow).