Crane fly - June beetle interaction?

I observed an interaction between crane flies and June beetles that puzzled me. I don’t know if this is unusual but I’ve never seen it or heard about it.

Craneflies are swarming right now. Last night they were buzzing around the large beetles like in this photo. This happened more than once, with various sized craneflies and different beetles. Then a cranefly would land on the beetle for a while, flit around and crawl all over the beetle, settle back down, and repeat. If I scared one away, it—or one like it—quickly returned.

Does anyone have an explanation for this behavior?


Do you think the beetles may smell good to the crane flies?

Maybe, but why?

Are they under a light? Maybe the crane flies are attracted to the light reflecting off the beetle’s shiny carapace? Although you’d see them swarming the bulb too if that was the case.

A quick Google didn’t turn up anything about the species interacting. The only thing I could think of is some kind of scent, like scharf said. Some crane fly adults eat nectar, if that’s a nectar-eating species maybe the june beetles were previously on a plant that left some pollen scent on them. That seems like a stretch though, especially since most crane flies don’t eat at all in their adult phase.


If someone identifies my crane fly, I’ll pay attention to what the adults eat.

Perhaps the beetle is just a handy perch near the light?

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I had a random thought. There was a lot of crane fy mating going on that week. Maybe the June Bugs were new adults, and smelled like soil, where some crane flies lay their eggs. They might be jumping around looking for a soft bit of soil to oviposit in… I don’t honestly remember whether I observed any of the smaller crane flies doing this. I believe the male crane flies are smaller than the females, based on the mating pairs I saw everywhere.

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