Last summer, a neighbor asked why we don’t see lightning bugs anymore. This summer, we’ve seen several posts on social media asking about the lightning bugs. Each of these concerns were about the lack of lightning bugs. But, last year we ended up with beautiful displays. Although threatened, we think many people expect these insects too early in the season.

Let’s start there. Yes, we will see lightning bugs this year. The reality is the impact of cool weather early this spring and recently. We are still below the 950 growing degree days (GDD) required for emergence. GDD’s are a measure of the growth and development of plants and insects during the growing season. In 2022, our GDD was 926 on June 14. This year it was 722. So, a continued warm up period should get us to 950 over the next few days so we can enjoy their light show again this year.

Secondly, the unusually dry weather could be impacting fireflies. So, the increased moisture is a good sign as GDDs continue to increase toward their emergence.

Thirdly, all insects go through cycles of booms and busts. Population cycles of insects can be affected by winter temperatures, moisture, humidity, predator populations, diseases and much more. We can see growing populations, then have a sudden crash. Eventually, populations begin increasing yet again.

There are threats to fireflies as well. Habitat loss from humans is a major concern. Light pollution and the use of pesticides are other factors. In your own yard, consider mowing higher this time of year to improve habitat.

Mulch more with leaves or wood much around plants to mimic the humus layer in the woods (just don’t use heavy mulch up against plants and tree trunks). Reduce outdoor lighting when fireflies are showing off — it will help them and allow you to have a better view of their show.

So, be on the lookout the next several days for their emergence and light show.

The name firefly, lightning bug or glow worm can be interchanged and belongs to the beetle family of which there are more than 2,000. With three body segments, six legs and an exoskeleton, beetles are distinguished by two pair of wings, one soft pair for flying and an outer hard pair called elytra for protection. Wet, warm weather finds them in trees, bushes and grasses, especially in natural habitats. So, while we commonly call them fireflies, lightning beetle is a better term to use.

In summer we can observe the fourth, or adult stage, but during the fall, the adults lay eggs in the ground, in humus or leaf layers, as well as other moist locations. These eggs hatch into larvae that will hibernate throughout the winter. These larvae will live underground feeding on the larvae of other insects and worms; many times they are feeding on the insects you do not want in your garden. In late spring, the larvae will become the third stage called pupae, eventually becoming the fourth stage — the adult insect we see flashing during our summer picnics and family events.

The firefly light is called bioluminescence, a combination of two chemicals called luciferin and luciferase. Oxygen combines with luciferin, regulating it to create the cold light energy we see. But why would an insect use flashing during the evening hours? Surely it is not just for our entertainment.

The first reason is for protection. A light attracts other predator insects, but it can also frighten them. Fireflies have a toxic chemical called lucibufagins that is distasteful to other insects and they will avoid catching them.

The second reason fireflies flash is for love in your backyard. The purpose of insects during their short life is to mate and lay the next generation of eggs. Signaling by flashing is one way to attract a suitable mate, however, it doesn’t always work.

Each firefly species has its own signaling pattern recognized by its own species. Some sneaky females will mimic the flashing of another species only to catch and eat the signaling male. Most frequently though, the same species male will show his best signal to the female until she signals back by flashing in return. If she accepts him, they exchange light signals, mate and eventually she will lay eggs in the soil, beginning the next life cycle.

Females usually remain in trees and bushes watching the male display his unique pattern, flying up then dropping quickly forming the letter “J.” Each flash takes only 0.2 to 0.3 seconds. Scientists using sophisticated equipment to measure sequences gives us a more understanding of their habits.

Watch this amazing video all about fireflies to get you and your children or family ready for the show this year at http://go.osu.edu/firefliesvideo.

Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County.

Kane Shipka is an Ohio State University Extension Master Gardener Volunteer in Mahoning County.