Malaise traps (flight intercept traps)

Malaise Trap - note the collecting bottle attached at the highest part of the tent

I’ve got to look into how these traps were named. It is the first sampling technique whose name tells you nothing about how it works. A malaise trap can also be thought of as a flight intercept trap. The ones that we used were the tent looking contraptions featured above. The “tent” is divided by a central wall. Upon running into that wall, some insects will fly upwards towards the top of the net. In that uppermost corner there is a passage which leads to a collecting bottle filled with alcohol (we are using 90% ethanol or dilutions thereof).

About 10 meters up in the forest canopy

The alcohol kills the insects and preserves them. The pitfall traps use soapy water because they are only meant to be set overnight. Malaise traps can be set up for longer periods of time. Short on time, we were only able to have them up for one or two days.

Diptera - Tabanid fly with striped eyes! Photo: Phil Wittman

Malaise traps target diptera (flies) and hymenoptera (ants, bees, wasps). Coleoptera (beetles) on the other hand, upon encountering a barrier will close its wings and drop to the floor. The malaise traps miss them entirely. This is also the first type of sampling technique that takes slightly more specialized gear. Though I bet a homemade one would be easy enough to construct.