Monday, February 8, 2016

FWS Student Highlights: Rachel Stocker

I have been working on a forensic entomology project with Dr. Joris van der Ham, from the environmental sciences department, since last April, though the first few months were for credit rather than through OSCAR. Historically, the time between a death and the discovery of a body (post-mortem interval, or PMI) has been determined using insect larvae. We’ve been working to see if the adults, which are easier to identify, can be used instead.

In the beginning, we put out beaver and pig carcasses and collected the insects that fell or flew into the traps around them. (And boy, did that smell good.) We collected the insects from mid-April to the beginning of August. Now we are working on identifying the insects.

On a weekly basis, I generally spill insects out into a Petri dish and look for characteristics to tell me what those insects are. For example, four wings mean that the insect is a wasp or bee; two wings mean the insect is a fly; and a hard shell behind the head means that it is a beetle. Once that has been determined, we narrow it down to family, genus, or species using dichotomous keys. The insects go into vials marked with their names and then into jars marked with the date they were collected, the collection site, and the kind of trap they were found in.

Slowly but surely, the number of insects in my vial marked ‘???’ goes down as I learn more families. Last week, I found a beetle that I couldn’t identify, and I spent almost two hours trying to figure out what the family was - but that paid off, because in the week since, I’ve found seventeen of those little jerks scattered across the samples, and I don’t have to look up what they are.

The biggest difference between now and when we started identifying last summer is that we’re no longer collecting. We’ve also found keys that use pictures instead of illustrations, which makes us more accurate in our identifications, and have begun putting data into spreadsheets.

I got into this project because I was interested in forensic entomology and wanted to have some experience with it before going to grad school to be certified as a forensic entomologist. It’s been an amazing experience.