Ask A Master Gardener – Fireflies

One of the sure signs of summer are fireflies or lightning bugs lighting up the night sky. You may remember catching them on a warm summer evening or simply watching the light show from a rocking chair on the porch.

Fireflies are not flies as the name would suggest; they are classified as beetles belonging to the family Lampyridae, which comes from the Greek “lampein” meaning to shine. There are about 2000 species of fireflies in the world. They can be found everywhere, except in Antarctica. In the western United States fireflies lack the ability to produce light, while in a handful of places throughout the world, there is a species that can synchronize their flashes.

Fireflies species live in a variety of habitats, with most species living near ponds, streams, marshes and lakes. They like humid, warm environments and long grass. The females need a moist habitat to lay her eggs. The long grass provides fireflies protection during the day, and gives them a better vantage point for signaling at night.  The best places to see fireflies are over meadows, fields or lawns, and at the edge of woods or streams.  Since fireflies are nocturnal, they are seen between dusk and midnight.

Both male and female fireflies produce a light that depending on the species, maybe yellow, green, or orange. The light comes from special organs on the underside of the abdomen. This light is a “cold” light called bioluminescence. The light show seen on summer evenings is for mating purposes. The male firefly is the one seen flying while flashing patterns of light to the female. In return, she signals her response from perches in or near the ground. In some species, the female is wingless.  This continues until they find each other and mate.  Each species has their own distinct flashing pattern. Scientists are unsure how these insects can regulate the off/on process of the signals.  The eggs and larvae of some species glow, which is where the name “glowworm” comes from.

Besides for being a mating signal, the flashing light of the firefly also serves as a defense mechanism. It’s a warning to potential prey that they are not very tasty. The light is also a way to defend their territory.

Fireflies are beneficial insects, in that they help to control pests. The adult firefly may feed on nectar and pollen, and some do not feed at all. It is the larval stage which is the most beneficial. The larvae are carnivorous, feeding on snails, slugs, and other soil-dwelling insects such as cutworms.

Fireflies may be on the decline due to dry winters, light pollution, pesticide use, and habitat destruction. Light pollution impacts the ability of fireflies to communicate through their flashing patterns, missing the opportunity to mate. To reduce light pollution, turn off outside lights when not in use. Other things we can do is avoid pesticides, use natural fertilizers, and allow their natural habitat to remain untouched.

Fireflies don’t bite, they have no pincers, they don’t attack, they don’t carry disease, they are not poisonous, and they don’t fly very fast.

Enjoy the light show.

Chris Jacobs

Certified Master Gardener

 

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