Mayfly, don’t bother us – don’t go away, either

Havana, Ill. —  Funny thing how those studying nature and wildlife before us were able to nail observations that we’d re-confirm over and over through the generations.

Take the peskiness of the mayfly, for example.

Those living in or passing through Havana in west-central Illinois in late June were seen marveling – and cursing – at a thick cloud of mayflies that swarmed a bridge across the Illinois River. While drivers shook their fists, entomologists shook their fingers, defending the mayfly, pointing out its value in the state.

This notion of mixed feelings wasn’t anything new.

Going all the way back to a 1953 report for the Illinois Natural History Survey titled The Mayflies, or Ephemeroptera, of Illinois,  you will find B.D. Burks writing, “In awe find that mayflies are important not alone to harass highway maintenance men and press photographers. They are much more so to those entrusted with the well-being of our fish populations, those interested in the public health and other values in inland waters, and those interested in the peculiarities of nature.”

Flash forward some 63 years later: On June 27, the Havana Police Department posted on its Facebook page, “Please use caution when driving across the bridge today. Last night there was an invasion of mayflies that has caused the bridge to be very dangerous. At one point they had piled 6 inches high and when ran over, became very slick. There were already motorcycle accidents due to this and cars stuck in the center of the bridge. Again, use caution.”

According to reports from The Associated Press, the mayfly invasion is not unusual to Illinois towns that sit along rivers like the Mississippi River or the Illinois River, which runs through Havana. Last year, a swarm of mayflies hit the bridge over the Mississippi that stands between Savanna and Sabula, Iowa. Transportation crews used snowplows to remove the insects in that case.

The Havana Street Department and the Illinois Department of Transportation worked together to remove mayflies in the more recent “attack.”

“Birds, for instance, are nesting, and they’ve got young at that time, so mayflies are a huge input of food for them at a critical time in the development of their young,” Nick Di Cresce, a naturalist  based in Michigan, told Entomology Today. “We have frogs, toads, and other amphibians that eat them, fish eat them, so mayflies are what’s on the menu.”

Scientists and entomologists note that mayflies hatch all summer long. The hatch provides a feast for lucky fish populations. It also benefits anglers keen enough to take advantage.

“As a part of the biological complex of our waters, for all mayflies are aquatic in their developmental stages, these insects find their most important place in human economy and interest,” Burks explained in his INHS report, which has been updated over the decades. “They are an important link in converting microscopic food organisms and vegetable detritus into units. They are large enough and of proper character to be of value to our predatory fishes. This fact has been employed by fly tiers in the design of certain artificial lures intended to be attractive to certain fishes.”

Interestingly, the morphology of mayflies is said to be similar to the morphology of insects that disappeared millions of years ago.

To those in Havana who dealt with the recent swarm and subsequent cleanup – crews hauled away three dump truck loads of mayflies – fly fishing wasn’t exactly one their minds.

“I have lived here my entire life and on the job for 31 years and I have never seen anything like that,”  Police Chief Kevin Noble said.

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