First published in the OSU Biomuseum blog on 2015-08-31; minor corrections.

Collecting insects is one of the many activities of the staff and volunteers at the Triplehorn Insect Collection. Each time we go out in the field and collect we create a tiny snapshot of the insect fauna of that specific place and date.  It’s far from complete, but adds to our knowledge nonetheless. We do not need to go far to find insects that no one has ever studied before. Even in our own backyard, next door to the Museum of Biological Diversity, we find new or rare insect species and discover new facts about known species.

One of the methods we frequently use to collect small flying insects is the pan trap – a bowl with water and a drop of clear, unscented liquid soap.  The soap breaks the surface tension of the water and makes the insects sink.  The color yellow (bright yellow!) attracts many insects, including the parasitic wasps that several of us in the collection study.  Our yellow pan traps, (or YPTs for short) are simple plastic party bowls.  For best results we leave the YPTs out in the field for about 24 hours.  After that we remove the catch, and start the cycle again: fill the YPTs with water, add soap, leave for 24 hours, remove catch. We usually set up 25-50 YPTs in one spot and that’s one sample.

There are a couple of variations on how to empty the traps: scooping the specimens with a fine fish net, or pouring the content of the trap through the net. Either way the specimens get separated from the soapy water, and then are carefully washed with clean water to remove all the soap residue. Once washed, the specimens are preserved in 95% ethanol and placed in a freezer.  That slows the degradation of their DNA and allows for molecular level studies.  Later, we sort the specimens into groups (beetles, wasps, leafhoppers, etc.) and start the long process of specimen preparation for study.  The YPTs are washed and saved for the next collecting season.

Collecting locality across the street from the Museum.

Collecting locality next door to the Museum.

Yellow pan traps are labeled with our name & phone number.

Set pans on the ground. Avoid direct sunlight, but don’t hide them.

Zach Hurley adding a drop of soap to each pan trap.

Zach Hurley adding water to each pan trap; Matt Elder harvesting the catch.

Choice of container to pour water is yours. Simple plastic jug does the trick. Just don’t overfill!

Alternatively, mix soap and water before adding to the traps. Photo by H. Clebsch.

Relax and let the YPTs work for 24 hours.

Single YPT after 24 hours in the field. Awesome catch!

Norman Johnson checking the content of the trap, remove twigs, leaves, and other debris.

Norman pours (or gently scoops) the content of the trap in fine fish net and discards the soapy water.

Zach Hurley demonstrates how to remove excess soap from the sample. He carefully washes the content of the yellow pan trap with clean water several times.

All specimens collected by the yellow pan traps that were set on the same day and harvested 24 hours later equal one sample.

Each sample is placed in a plastic bag containing ethanol 95% for better preservation. Each bag gets a collecting label.

In the lab we sort specimens in each sample to large groups (ex.: beetles, wasps, leafhoppers, etc.)

Zach Hurley sorting the sample under a microscope.

At the end of the season we wash, dry and save the yellow pan traps for next year..

A heartfelt thanks to the people in these photos: Zach Hurley, Matt Elder, Norman Johnson, Hans Clebsch; and to the anonymous biker going by the Museum building.

About the Author: Dr. Luciana Musetti is the Curator of the Triplehorn Insect Collection at Ohio State University. All photos are courtesy of the author, except for the one of Hans Clebsch.