Wood Cockroach

2023 November 5

When we had our annual cider-making party on September 23, 2023, we mostly used the apples on our own property but some people brought apples from their own trees. And one batch of apples had a couple of these insects on them that were nothing that I had seen before.

These are obviously some kind of cockroach, the body shape is extremely distinctive. The thing is, though, as I have noted before, we don’t normally have cockroaches up here in the Keweenaw! For most species, it apparently gets too cold for them outdoors, and too dry for them indoors. So, this is something new for the area!

When I first started taking pictures, there was a gray object attached to the tip of the abdomen.

But she apparently got agitated enough to drop it, so that we can see that it is a structured object and not just a piece of fecal matter. In fact, I am pretty sure it is an ootheca, or egg case, which means that this is a female.

Once that was dropped, we can see that the wings are longer than the abdomen, which is pretty suggestive that this is one of the species that can fly.

They eyes are interesting, and not quite like the compound eyes of any other insects I have photographed. They almost look like multicolored glitter balls.

And, of course, from the side she has that characteristic cockroach profile.

But that leaves a series of questions:

  1. What kind of cockroach is this?
  2. What is she doing here?
  3. Is this going to be a problem?

OK, so first off, rummaging around on BugGuide for the few roach species that have been found anywhere near here, I would say the most likely candidate is the Spotted Mediterranean Cockroach, Ectobius pallidus. These are, as one might guess from the name, an accidentally introduced (and maybe invasive) species from Europe.

Second, we haven’t seen these before because they only just got here. According to the Michigan State Extension Service, spotted_mediterranean_cockroaches first hit North America on Cape Cod, Massachusetts around 1948. They subsequently appeared in Southeastern Michigan, and then hit Traverse City (in the Northwestern part of the Lower Peninsula) in 2008. And now, they have apparently made the jump across Lake Michigan to the Upper Peninsula, most likely by hitch-hiking on cars, although I suppose they could have flown across on their own.

And third, now that they are here, I expect that they are likely to go through the standard population explosion that is typical for invasive species when they first hit an area. It will take a few years for the local predators to figure out that they are something to eat, and for diseases from their home territory to catch up with them. Luckily, these do not appear to be one of the kinds of cockroaches that can live and reproduce in houses. They may get in from time to time, but mainly they will breed outdoors and tend to stay out there. They are fairly standard detrivores, and so I expect to find them in decomposing woodpiles, compost heaps, and under rocks. Along with the woodlice, millipedes, and earwigs. So, maybe a bit of a nuisance when they get into everything for a while, but most likely not a long-term problem.

Or, at least, so one hopes.

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