Yellow pan traps are an invaluable collection method for microhymenoptera. Popularized by Lubomír Masner, the trap consists of a yellow plastic bowl filled with water and a drop of soap. The purpose of the soap is to break the surface tension so that insects fall into the water and drown, allowing them to be collected.
As part of an outreach activity on collection methods, I put out 50 yellow pan traps in a flower garden near the Frost Entomology Museum. The traps were only out for four hours, between 1:30PM and 5:30PM, but even after such a short time we still captured a large amount of insects. There were wasps trying to land in the pan traps before I even filled them with water!
When I sorted through the sample, I was shocked to find over 50 ceraphronoids from just a few hours of collecting. I found Ceraphron, Aphanogmus, and even one female Dendrocerus specimen, my first Megaspilidae of the month! I got more specimens in four hours of pan trapping than I did in a week of malaise trapping.
If you collect or study microhymenoptera, do not underestimate the value of yellow pan trapping! In this case, minimal effort yielded maximum results!