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.
