Where Are the Lightningbugs?

It’s still too early to know what the lightningbug population will be this year.  Be patient.  A few adults have already been spotted, but most lightningbugs will arrive around the Fourth of July.  Adults live for a few weeks, during which time they must attract a mate (the purpose of the light!), mate, and lay eggs.  In most years, lightningbug populations fade quickly, and most are gone by the end of July.

The Oddity of Insect Names

Lightningbugs are also called fireflies which is peculiar because they are neither bugs nor flies.  Lightningbugs are beetles.  They are soft-shelled beetles rather than the familiar hard and crunchy beetles such as Junebugs and Japanese beetles.  You can prove they are beetles by examining the top side.  When you are done admiring the light-emitting segments at the end of the underside of the abdomen, turn the firefly over and notice how the wing covers meet in a line down the middle of the back.  The line-down-the-back is a characteristic of almost all of the beetles. 

The summertime enjoyment of watching lightningbugs twinkle and dance across the lawn, field, or garden appears to be on the decline.  At least for some of us.  Lightningbugs, like most insects, vary greatly from year to year and place to place.  Some people ask why there are so many lightningbugs, while others ask, in the very next phone call, how come they haven’t seen any.

One possible answer for the low numbers of lightningbugs is to blame the weather (what else is new?).  Lightningbugs have a complete life cycle, and the larvae thrive in damp locations such as under mulch and plant debris, where they feed on snails, slugs, worms, and other small critters.  Yes, lightningbug larvae are cold-blooded predators, making them beneficial if they are eating the slugs from under your hosta plants.  Dry weather and droughts during the fall of the past few years may be interfering with lightningbug reproduction and survival.  Less moisture on the ground means fewer suitable habitats for lightningbug larvae and less food (slugs and snails).

We want lightningbug displays that rival the memories of our youth, but that might be wishful thinking.  Instead, for best viewing chances, drive to a natural area in the country on a warm, humid, July evening, park safely off the traveled portion of the road, and hope for a dazzling display.

More about lightningbugs is in our online article at https://hortnews.extension.iastate.edu/lightningbugs

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Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 18, 2021. The information contained within may not be the most current and accurate depending on when it is accessed.