Chesapeake Native Gardens: Got Fireflies?

Less work now begets more fireflies next summer.

This past summer, on a block of row and single family homes nestled fairly close together, our garden attracted more young visitors around dusk than usual. It seems as though we had a good firefly spotting spot and kids noticed. We have an open lawn in front and I wondered if that made it easier to see fireflies or if there were other factors at work.

Meadow at Adkins Arboretum in Maryland

Turns out there were likely many things at work! Fireflies, a type of beetle, like to hang out in moist shady areas so a lawn surrounded by layered shrubs and trees, or a meadow surrounded by forest, is a good place to look for fireflies at dusk in June.

Scientists say young fireflies, firefly larva, live in moist leaf litter, sometimes waiting two years before emerging for their short adult life. Leaving fallen leaves in your garden beds now will help the young fireflies over winter. Blowing leaves, or raking and bagging leaves, actually eliminates the homes of the young fireflies, if not the fireflies themselves.

Heuchera 'frosted violet' in a bed where fallen leaves remain; in spring, plants and bulbs easily push new growth through the leaves.

This gets a bit tricky in a setting like ours where smaller lots are bordered by large street trees and there are lots of leaves come fall. In recent years, we left as many leaves as possible in the garden beds and raked leaves from the grass to the beds. If you have an area where you can pile leaves and let them decompose, all the better. Decomposed leaves called 'leaf mold' are also one of the best compost materials around.

Scientists say it is also crucial not to spray or fog for mosquitoes during summer months. Even naturally derived sprays indiscriminately kill fireflies and other beneficial insects.

Experts suggest adding a water feature to your garden if possible. Providing water helps fireflies find dampness. To prevent mosquitoes from breeding in that water, it should either be moving (mosquito larva don't breed in moving water) or, for standing water, you can add mosquito dunks recommended by scientists like Dr. Doug Tallamy and available at hardware stores and garden centers. Dunks aren't harmful to birds and pets and prevent mosquitoes from breeding in standing water.

Layering perennials, shrubs and trees can also provide the shade fireflies seek. Fireflies like to live in long grasses too. Some people are letting their grass grow longer in defined areas of their lawn for just this reason. Another way to help is to reduce your lighting at night. Artificial lights disrupt firefly mating cycles. Even turning off just a few lights will help.

Where do native plants come in? Fireflies on the east coast are said to be carnivorous so they eat things like snails and slugs. Native plants create the habitat in which all of these small creatures can thrive in even the smallest of spaces.

After it's all said and done, I really don't know exactly why we had so many fireflies this year but I am sure glad the small observers noticed. Thanks for gardening for the Chesapeake!