Inviting Fireflies to the Garden: It Starts in Fall!
Did you catch the magic of fireflies in the garden this summer? If so, support them all year with easy steps in fall (including less end-of-season maintenance). If you missed them, measures to increase garden biodiversity may help lure them. Not only flashy, but they also bring predatory and pollinator benefits. Gardening expert Katherine Rowe explores how to invite fireflies to the garden with a foundation this fall.
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Fireflies, with their bioluminescent flashing, bring back childhood memories of summer evenings spent outdoors. They’re the reason people flock to designated natural areas each summer to witness the spectacle of their synchronous light show.
In addition to their glowing charm, there are ecological benefits that vary among the numerous species. As beetles, fireflies pollinate crops and ornamentals as they forage for pollen and nectar. In the lengthy larval stage, they’re natural pest managers.
There are steps we can take to foster fireflies (and many other species) to increase habitat and biodiversity in our own small corners. Fall is the optimal time to invite fireflies to the garden by creating a foundation that keeps them year-round. As fall becomes a quiet winter landscape, a supportive habitat is essential to fireflies, native bees, butterflies, moths, and so many others to continue their ecosystem roles.
Inviting fireflies to the garden begins in the fall. Building a habitat is as easy as letting natural resources do their job and allowing a little rewilding, with small steps to increase garden diversity. Come summer, maybe we’ll be fortunate to catch their glimmer at dusk.
About Fireflies
Fireflies belong to the Lampyridae family, with about 22 genera and 200 species in North America. They occur in every state in the U.S., and on every continent except Antarctica.
There are numerous species (over 2200), though fireflies are experiencing a population decline. The beetles have the special power of bioluminescence to flash in the evening sky, mostly active at dusk and nighttime.
Lightning bugs flash to communicate and locate mates. Each nocturnal species has its own flashing pattern. Even the larvae as glowworms emit light, this time to warn predators of natural toxins. Some firefly species are active during the day and use pheromones, rather than flashing, to communicate.
Fireflies spend much of their lives in the larval stage, from two months to two years or more. They spend this stage under leaf litter, burrowed into the ground, or in logs and decaying bark. They overwinter in these protective layers until emerging in spring and maturing in the summer. Adult fireflies live for about a month in the warm season.
Their Roles
Beetles have an ancient record among the first pollinators, and fireflies continue the role as nocturnal pollinators. Eastern fireflies (the flashing species found east of the Rocky Mountains) feed on nectar and pollen as adults.
Fireflies are classed as beneficial insects to gardeners as natural pest control for soft-bodied invertebrates (slugs, snails, worms) and other insects. Many species have carnivorous larvae that feed on other insect larvae.
The first step in fostering fireflies in the garden in fall is to avoid applying broad-spectrum pesticides in beds and lawns, which harm the insects themselves and their food sources. Next, increase natural elements and plantings to provide shelter and forage.
Leave the Leaves
Attracting fireflies to the garden in fall begins with leaves. There’s a world of biodiversity that occurs beneath the leaf layer, which provides refuge until spring’s reemergence, when the beneficial insects work to balance our gardens through pollination, pest management, and increasing the food web.
Leaving the leaves is a firefly-friendly practice, just as essential as planting flowering perennials, shrubs, and trees. The decaying leaves, twigs, and bark (the duff layer) are prime habitat. Leave some logs and rocks in place, too, for added shelter sites.
As leaves naturally drop from deciduous trees, shrubs, and herbaceous perennials, they create a layer of coverage at the base of the plant. They promote habitat for songbirds, small mammals, reptiles, amphibians, and insects like beetles. The creatures that live in our gardens in spring and summer remain during the cool season with a supportive habitat, even if more hidden and less active.
Many species overwinter and lay eggs in fallen leaves. Earthworms and other invertebrates inhabit the underlayer and convert organic material into nutrients. Fireflies and other beetles dwell in the leaf layer, as do bumblebee queens who bury themselves in the leaves to overwinter. Butterfly and moth pupae, too, dwell beneath to emerge in spring.
Whether making mulch layers or piles for leaf mold, wait until spring’s temperatures reach the mid-fifties to thin leafy layers or make use of piles. This gives nesting insects time to emerge in warm conditions.
Mulch Beds
There are several ways to utilize leaf drop in the landscape to help fireflies in the garden in fall. Leaves are a renewable resource, right from the branch, and a mulch, compost, and soil conditioner all in one. They provide insulation, moisture retention, weed suppression, and nutrition through decomposition.
A top way to easily use and consolidate leaf litter is in garden beds and around trees. To use leaves as mulch, incorporate them as a natural cover across bare areas of beds and around plants. Leave leaves where they drop or lightly rake whole leaves into beds to add insulation for roots as temperatures drop.
Apply a thick, three- to five-inch layer. Keep the layer off of woody stems to prevent fungal problems and maintain air circulation. For borderline hardy specimens like roses and hydrangeas, depending on the climate, add a layer of leaves atop the crown in dormancy for added winter protection.
Piles for Leaf Mold
Piling leaves is sometimes the easiest way to move them out of sight while putting them to future use. The leafy piles create sheltering sites over the winter. As the leaves break down, they form leaf mold, which is valuable as a soil conditioner.
It takes about six months to achieve completely broken-down leaf material, but a working pile is a valuable resource for amending native soils at planting and for topdressing.
Incorporate Native Flowering Perennials and Grasses
Aside from keeping the leaves and duff, native plants and grasses create habitat for fireflies. Fall is optimal for planting and expanding our garden collection, and a diversity of plants attracts the most firefly species (as well as hundreds of other species).
Planting pollen and nectar-rich plants now sets the foundation for next season’s beneficial insect support. In autumn’s moderate conditions before heavy frost, plants establish strong root systems to survive winter.
Native plants have specific attributes that match the needs of native pollinators, and they adapt to their growing environment without requiring extra resources. Top natives for fireflies include milkweed, solidago, coneflower, aster, and grasses.
Lightening bugs use grasses, even tall ones, from the base to the blades, as hiding and landing spots. They take shelter in tall grass during the day and fly into the trees at night while signaling for a mate. Look to native grasses like switchgrass, big bluestem, blue fescue, little bluestem, and blue grama for region-specific ornamentals with ecological value.
Fireflies prefer moist sites, with ferns and grasses helping retain soil moisture. Create naturalized shrubby areas on the yard’s perimeter for added shade, moisture, and sheltering opportunities.
Mow High
Turf that’s clipped short doesn’t provide resources for fireflies in the garden in fall. Without a spot to land for signaling mates, to feed, or nest, it lacks habitat value for the beetles.
To increase the hospitality of the lawn, keep it on the high side. Grass around four inches high during the growing season, rather than very short, is more likely to invite fireflies.
Fall is a good time to consider reducing lawn areas and increasing surrounding bed space and plantings. If you’re considering a lawn alternative or reduction, doing so now or in spring planting boosts garden diversity for the active season.
Add a Water Source
Many fireflies prefer moist sites and have a natural habitat of moist woodlands and meadows. A natural body of water makes a good firefly sanctuary, or a small fountain, pond, or puddling area promotes damp situations they’ll frequent. Wet areas house the food sources that firefly larvae eat, including slugs, worms, and insects.
If mosquitoes are an issue, consider a dunk tab, which won’t harm fireflies or other beneficials. Try plants with essential oils that act as natural repellents, too.
Reduce Outdoor Light Competition
To host fireflies in the garden in fall is to let their light shine. As their primary means of communication, the insects need dark sites where their flashing is visible. Lessen the intensity of bright outdoor lights to prevent interference with the bioluminescence.
Turning off outdoor lights during their most active times (about 30 minutes after sunset and for several hours after), or installing motion sensors, helps with darker conditions. Aim any lights downward, rather than outward, and use red bulbs when possible. Fireflies don’t register red as well.
