GARDEN TALK

Based on adult courtship behavior, fireflies are categorized into three groups: flashing fireflies; daytime dark fireflies; and glowworms. The eggs can glow as well, but the intensity is very low. The light serves another purpose for the firefly, too: These insects taste bitter to predators. The glowing identifies them to predators, and the predators avoid eating them.

In 2021, researchers completed a risk assessment of fireflies and found that 14 percent of the firefly species are threatened by extinction. Several factors contribute to the decline of firefly populations, including habitat loss due to urban development, light pollution, drought, incorrect use of pesticides and the use of lawn fertilizer.

Like all beetles, the firefly has a complete lifecycle consisting of four stages: egg, larva, pupa and adult. The adult female lays eggs in moist places near the ground around mid-summer. The eggs hatch into firefly larvae in about two or three weeks. The firefly will spend most of its life as a larva in the soil or under tree bark, which could last well over a year. The adult stage of the firefly will only last a few weeks.

Fireflies are considered beneficial insects, and it is the larval stage that is the most beneficial. The firefly larvae are predators of snails, slugs and other soft-bodied insects; however, firefly adults are not carnivorous at all. Some species eat the nectar or pollen of flowers, others eat smaller fireflies, and some do not eat anything at all.

There are several things we can do in our landscapes to help firefly populations.

n Decrease light pollution by turning off exterior lights during the firefly mating season.

n Allow low-hanging branches to remain on trees and shrubs.

n If possible, allow some natural areas to remain with leaf litter and tall grasses.

n Adding a water garden to the landscape may encourage fireflies because the firefly larva likes damp soil.

n Reduce the use of lawn fertilizer and pesticide, if possible.

n Try to avoid using broad spectrum pesticides and broadcasting them over large areas.

Understanding and managing the desired habitat for fireflies is important as we help encourage these beneficial insects.

The larvae of all firefly species are bioluminescent, but not all adults produce light. The light is a chemical reaction. Larvae use their light as warning displays to ward off potential predators, and adults use the light to signal each other and attract mates. Scientists also use the flashing pattern and color to distinguish between different species.

Multi-tasking Tails

Previous Pages: Fireflies use light flashes as mating signals. The blinking lights that you see in your yard are generally from males looking for females. Above: In addition, the lower abdomen of a firefly makes it bitter tasting to predators.

For additional help with home and garden information, contact your local county Extension office or visit aces.edu.

~ Dr. Chip East is a regional agent for commercial horticulture for Alabama Cooperative Extension.