Gardening for Fireflies

Tigertown Farm
1 day ago
4 min read

Many of us have fond memories of watching fireflies light up backyards on warm summer evenings or catching them in jars and watching their mesmerizing patterns. We've heard many folks observe that they hardly see these magical little creatures around anymore. Ecologists are learning more about firefly life cycles, and honing on what we can do to help. Our top recommendations are to leave leaf litter to decompose in place wherever possible and remove unnecessary outdoor lighting to allow their luminous mating rituals to go undisturbed. Learn more about these fascinating creatures and see our full list of action steps ahead:

What are fireflies?

The word "firefly" actually refers to a large family of beetles called Lampyridae,

which includes both fireflies and glow worms. While there are over 2,200 species within this family across the globe, there are only 167 that live in North America.

To really understand how to help fireflies, we need to start at the beginning: a firefly egg. Eggs are laid in moist soil duff, leaf litter, or rotting wood. And fun fact: some firefly eggs might glow slightly! After around 2-3 weeks, the eggs will hatch to reveal... well a sort of weird looking glowing caterpillar-esque creature. This is the ferocious and very hungry larval stage. They will spend their time hunting soft-

The larval stage of fireflies is... uhh... pretty alien looking. © Anita Gould via iNaturalist

bodied invertebrates like snails, slugs, and earthworms (delicious), while avoiding spiders and other larger invertebrates that might eat them (scary!). Fireflies spend the majority of their life in the larval stage- up to 2+ years! In fact, this is the stage of life that their bioluminescence initially evolved in; it serves as a warning to potential predators that they taste really bad. Firefly larvae of all species glow, but only a subset of species retain this ability in adulthood.

After satiating their juvenile hunger, many species will pupate in leaf litter, rotting wood, or underground before emerging as adults in late spring or early summer. The adults of most species will not eat for the rest of their lives, having obtained enough energy during their larval phase to sustain them throughout adulthood.

Black Firefly (Lucidota atra) is a Northeastern firefly species that doesn't bioluminesce. (c)Katja Schulz via iNaturalist — Black Firefly (*Lucidota atra*) is a Northeastern firefly species that doesn't bioluminesce. (c)Katja Schulz via iNaturalist

Many (but not all!) species light up during warm summer evenings as they conduct their flashing courtship dances. Each species has their own language (flashing pattern) that they use to communicate!

Happy Homes for Fireflies

There are many species of fireflies, so they can be found in pretty much any habitat that has enough moisture! Water availability is the most important consideration for most firefly species, but as long as that condition is met they can be found everywhere from grasslands to forests to marshes. They also need food sources (those tasty earthworms and slugs), a safe place to overwinter (like those cozy leaves or rotting logs we talked about earlier), no pesticides, native vegetation, and dark nights so that they can flirt with each other.

Help Out a Firefly Family

There are a few easy things you can do to help encourage fireflies to use your yard as a home.

Find out who's there! Make observations and post them on a platform such as iNaturalist or the Firefly Atlas to help scientists understand more about these creatures. If you recognized a trend earlier, it's that we just don't have enough data on fireflies!
Say no to pesticides. Many insecticides will also kill fireflies or their food sources! Fireflies can also help you out in the garden as a natural pest control as they will eat some common garden pests.
Leave a few areas "unkempt" or natural, perhaps with some dead logs or rotting wood in it to give them a place to lay eggs and overwinter.
Leave the leaves to give them more habitat and to retain moisture in the soil.
Mow less frequently: mower blades can directly kill firefly larvae and adults that are living in the grass. They don't move fast!
Mow higher: longer grasses can give larvae and adults more shelter and help retain moisture.
Keep an eye on light pollution. Fireflies require dark nights so that they can talk to each other with their flashing lights. Anthropogenic light sources are a major disruption, so make an inventory of what's coming on and rethink if they're necessary. Do you have garden lights that automatically come on at night even when they're not being used? Exterior driveway lights? Path lights? Try to put them on motion detectors or automated timers so that they only come on when needed and try to limit the amount of hours per day they're on for. If you do need lights, use dim red light bulbs to reduce firefly interference. Landscape lighting (such as for pathways) can be low and pointed to the ground. Use curtains or blinds at night to reduce the amount of light coming from your house.
Finally... our favorite... PLANT NATIVE PLANTS! Fireflies need a variety of plant heights and structures at different stages of their lives and plants also help retain moisture. Make sure you include several different types of plants such as grasses, flowing plants, shrubs, and trees. If you provide a diversity of habitat, there's a greater chance of attracting a variety of species.