Gender Identity – Milkweed Bugs

Distinguishing markings on the abdomens of a female and male milkweed bug (Lygaeidae: Oncopeltus fasciatus).

So one random factoid I encountered while researching milkweed bugs last week is that you can distinguish males and females by the markings on the underside of their abdomens.  Females have a black stripe and two black dots, while males (the smaller sex) have two black stripes.  I didn’t have a male to draw comparisons against last week, so I tracked down a neighboring lab colony of milkweed bugs and sure enough, boys and girls!  (Thus resolving any future crises I may have involving the gender identification of milkweed bugs.)

I had originally wanted to photograph a mating pair, but apparently they found being repeatedly flipped onto their backs disruptive.  I finally resorted to sticking them in the freezer for a few minutes, after which they gave a very good impression of being dead (slightly too good an impression).  Luckily they eventually perked back up and I got a few photos.