Written by Joe Ballenger

Nancy received this question on @RealScientists this week, and given that I’ve seen the first few wasps of the season already, I thought it would be a really relevant one to answer.

@realscientists seeing a change over last 10 years, many more of these open nest wasps and less of paper nest type. Curious, any thoughts? pic.twitter.com/qDshKPWzDn

— Peter Griffiths (@pggriff) March 5, 2017

I think this is a really great example of observations by a homeowner. If you own a house, and need to deal with the wasps in your rafters, you’re going to notice when the wasp species change.

…and the species of wasps around your house probably are changing.

In North America, there’s an invasive wasp species called Polistes dominula which is displacing our native wasps. It’s pretty good at pushing them out, too. They establish their nests earlier, make lots of workers, put them in tighter spaces, and will eat just about anything. When P. dominula appears, our native paper wasps leave pretty quickly…because they can’t compete.

The majority of research on P. dominula that I’m aware of has looked at its effects on our native Paper Wasp species (P. fuscatus, specifically), which is why Peter’s post is interesting to me. According to him, it’s pushing out a group of wasps which include Yellow Jackets and Hornets. I’ve worked with these insects before, and this is new to me…but I wouldn’t be surprised if they’re out-competing other types of social wasps. I just haven’t seen this specific question addressed in the literature.

Unfortunately, I can’t ID the wasp on the right with a high degree of certainty. The space behind the eyes is black, and while that’s not common, a lot of Hornets and Yellow Jackets have similar coloration and markings which means I need pretty high-res pictures at specific angles to attempt an ID.

Still, I think this is a really cool and interesting observation. I also think it’s one which would be interesting to see followed up with further research, because the answer could tell us more about why different species of wasps are so good at spreading to other parts of the world.