Mayflies at Cedar Point

2017 December 30
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On June 15, 2016, we took a trip down to southern Michigan/northern Ohio, and one of the things we did was take the kids to Cedar Point. While we were there, they were having a fairly significant emergence of large mayflies. They weren’t numerous enough to be a really serious issue, but they were pretty much everywhere if you took a moment to look. Like on this poster for a face-painting booth:


(the face-painting poster showed the girl very close to life-size, so you can see that the mayfly was pretty significant size).


Most of them were brownish-gray, but we did find one that was still white, probably due to just having emerged from its previous skin. Mayflies are unusual among insects in that they actually have two winged forms: the first one is when they first emerge from the water. They then fly off, land somewhere, and then molt again, which results in something like this white one. Once it hardens and darkens, it then flies off to mate.


I’ve posted mayflies before and noted that they don’t have fully developed mouthparts, and so can’t eat. This next photo shows that pretty clearly: whatever that mess is it has for a face, it certainly isn’t going to be able to function as a mouth!


The large eyes, and small antennae, suggests that they seek out mates by sight, not smell. It is amusing the way the top half of the eyes is brown while the bottom is black, making it look kind of like it has half-closed eyelids.

I understand that all around Lake Erie, mayflies like these are fantastically common, and sometimes make swarms so large that they are a traffic hazard due to all the crushed mayfly bodies on the road making the pavement slippery (not to mention obscuring the driver’s view by getting smashed on the windshield). Luckily, we weren’t there on one of those days.

Also, if you look at that first picture on the poster, you can see another insect near the girls’ eye. It was one of these:


It’s a male midge. You can tell it is male by the big fluffy antennae. Unlike the mayflies, the midges have well-developed antennae and unexceptional eyes, which pretty strongly suggest that they find mates by smell, not by sight. I expect that whether an insect goes for sight or smell depends on whether they normally mate during the day, or during the night.

One Response
  1. Carole permalink
    December 30, 2017

    Very nice. Hope there were birds to enjoy the bounty.
    Happy new year.

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