Hitchhiking mites, yikes (maybe he should have brought a towel)

One of the emails we got this month led to an interesting answer. A nonprofit director asked some questions about an earwig for their kids they teach. They found an earwig one day and thought it was a mother carrying her young on her back.

The questions they asked had to do with maternal care. Questions such as, “how do the babies get fed?” and “How long does she carry them?” At first, I answered the questions thinking about how long earwig (Dermaptera) mom’s care for their young. I also asked for a picture because I thought it was odd that the babies (nymphs) were on her back. That’s weird, right? As an entomologist, I know a lot about bugs, but there is a lot I don’t know. Particularly about groups of insects I don’t typically study. In biology I try to tell myself, “never say never.” As I waited for a picture, I looked into it more and couldn’t find a single reference about an earwig species that carries her young on her back.

Shortly after I asked, they sent a picture. I let out a “gasp!” and thought “that’s not a female earwig… it’s a male! So those must be parasites on his back.” From what I can make out from the photo, it appears to be mites on the earwig’s back. There are mites which are phoretic (i.e., hitchhiking) on earwigs, but with so many, it’s got to be a problem for the earwig.

A male earwig with what appears to be mites on his back. Photo from email sender.

How could I tell it’s a male earwig? The pitcher-like things at the end of their abdomen are called “cerci.” In male earwigs, the cerci are strongly curved whereas females have a slight curve. From what can be seen of the photo sent via email, the cerci appear to be strongly curved. Also, the nymphs of earwigs tend to be pale in color. 

A female earwig which was guarding her eggs. See how her cerci aren’t strongly curved? Photo was taken in Ecuador by Joanie.

So gross, yet so cool.

References:

European earwig – Forficula AURICULARIA LINNAEUS. (n.d.). Retrieved March 24, 2021, from http://entnemdept.ufl.edu/creatures/veg/european_earwig.htm

Strandberg, J. O., & Tucker, L. C. (1974). Filariomyces forficulae: occurrence and effects on the predatory earwig, Labidura riparia. Journal of invertebrate pathology24(3), 357-364.

About JoanieTheEntomologist

PhD candidate in entomology.
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