Aphodiini Beetles in Pocket Gopher Burrows

Gopher Burrow Trapping in Native Prairie!

One of the beetle groups that I enjoy collecting is the scarab group “Aphodius” (now split into numerous genera). Some of these species are generalist dung feeders, and some feed on detritus, but a large percentage of them are specialists. Many inhabit rodent dens & burrows and are host specific. The insects that inhabit pocket gopher burrows are active only in the winter, which gives a collector something to do in the off-season besides pinning and labeling things! I have done a lot of trapping for Aphodiines in pocket gopher burrows in New Mexico and Arizona. I even had a chance to do some trapping in Nevada (in sub-zero weather conditions) which I described in this article for Scarabs.

The insect species that we find in gopher burrows are highly specialized and usually occur nowhere else. I usually get an assortment that includes a number of different kinds of flies, camel crickets and beetles. Of the beetle families usually represented there are Aphodiines, Leiodids, Carabids, and occasionally something else like a Histerid, Staphylinid, etc. All the insects that I trap are saved, non-Coleoptera are sent to the Florida State Collection of Arthropods (FSCA) as they are all rare or unknown species.

The procedures for trapping are set forth in this article I wrote for Scarabs. Basically, you need to set a pitfall trap in a gopher tunnel and set gopher traps in the tunnel on either side of the pitfall trap so that the gopher doesn’t ruin the set. The whole thing needs to be covered over with a board and then soil, then left for a week or so. I have been saving the trapped gophers (along with collection data) and donating them to the University of New Mexico who adds them to their mammal collection. All the specimens I have collected in Arizona and New Mexico have been Thomomys bottae.

At Thanksgiving I had the opportunity to visit family in southeast Nebraska. Knowing that there are pocket gophers in the area, I shipped my supplies up ahead of time. We took a 4-wheeler and scouted for sign in the fields and property owned by my parents – nothing. We looked in an alfalfa field (usually very productive for gophers) across the road owned by friends – nothing.  Finally, with the help of a local farmer, we found some fresh gopher sign (mounds of freshly dug soil with no holes in it) in a native prairie. Soon, there were two traps set – now to wait…

Actually, I had tried trapping in gopher burrows once before in Nebraska, but all my traps were buried and nothing was collected. I hoped this time would be different! The gopher species here – Geomys bursarius halli – is different than I am used to, and are a lot bigger than T. bottae.  They are also possibly more wary. Being a different host as well as a different habitat and a different part of the country, all the beetles I would collect here would surely be new for me. I could hardly wait to see what was in the collection cups!

With a storm forecast and bad weather coming, we headed out to check the traps the afternoon before we were to fly home. There was a strong wind blowing which made us colder than ever riding the 4-wheeler out to the trapping site. We carefully removed the cover of soil and boards on the first set – the trap was unmolested! But alas, no insects in the pitfall! One more chance – we did the same with the second set. Same story! This time, however, there was a gopher in one of the traps. It was positively huge compared to the small T. bottae I am used to!

It was disappointing to have gone to the work of setting up the traps, and to have killed a gopher, all without collecting any insects. In later correspondence with others who have tried trapping Aphodiines in southeast Nebraska, I found that my experience was not unique. Apparently, these beetles are just plain hard to collect, and nobody knows what is going on. I can’t wait for another chance!

This past summer I learned of another way to try trapping the insect inhabitants in pocket gopher burrows. This method involves creating an artificial gopher burrow with a pitfall in the bottom and a small opening to the surface. The Aphodiines apparently search for new gopher burrows visually when they dispurse, and will sometimes use these artificial burrows. I want to try this technique at the Hassayampa River Preserve as part of my effort to sample the beetle species present. I have not been able to work in the real gopher burrows because The Nature Conservancy biologists don’t want to lose any of their pocket gophers in the name of science.