Firefly conservation starts at home — in our yards and in our parks

Fireflies, also known as lightning bugs, are neither flies nor true bugs. They are beetles, and like ladybugs, are cherished as one of our most well-loved insects.

Who hasn’t chased after a fading green blink as dusk descends? Most people have fond memories of running after flashing fireflies. Some may miss the summer nights when it seemed the whole night was lit up by bright flickers.

It is becoming more difficult for these insects to survive in our world; their numbers are dwindling due to habitat loss and degradation, light pollution, pesticide use and climate change.

But just as people attract butterflies to their yards, we can work to provide for and attract fireflies.

My daughter took a course at the University of Florida on the natural history of fireflies. It was taught by Dr. James Lloyd, who made a life’s career studying these intriguing creatures. She learned that just as there are many distinct butterfly species, there are also many firefly species, including 45 species found in Florida.

Fireflies have developed an amazing method of communicating using bioluminescence. Each species has a unique code, or flash pattern, that they use to find a mate of their species. Fireflies need darkness to see and understand their fellows’ flashes.

As individuals, we can turn off all outdoor lights around our houses, including flood lights, porch lights and garage lights. For security and safety, try using a motion-detection fixture. As a neighborhood, we can ask the city to put shields over streetlights to direct the light onto roads and away from yards and natural areas.

To attract a diverse firefly population, it is critical to provide a diversity of habitats. For example, some species live in the upper branches of trees (Photuris versicolor and Pyractomena borealis), others live in shrub layers (Photinus sanguineus and Pyractomena angulate), and still others live in grassy openings (Photinus collustrans).

At home, we can allow edges of our yards to grow up into shrubby areas or plant shrubs at the edge of a lawn. Better yet, if you like a more natural look to your yard, stop mowing a patch of your lawn and allow wildflowers and grasses to establish there, mowing it once a year. City and county park managers could promote a variety of habitats from open woodlands to grassy meadows just through proper mower management.

Leave some corners of your yard a little wild. The larvae of fireflies thrive in moist habitats with abundant native vegetation and dense leaf litter. Think somewhat woodsy with tall trees, medium trees, shrubs, native ferns and leaf mulch. This type of yard provides habitat for snails, slugs, earthworms and other invertebrates that ground-dwelling firefly larvae need to eat.

This type of habitat also provides safe places for firefly larvae to overwinter. Some overwinter in crevasses on tree bark, while others live in underground burrows or in rotting logs or leaf litter.

Fireflies are insects, so they are susceptible to lawn chemicals. Fireflies may be most vulnerable during their larval stage, which can last up to two years. Adult fireflies may only be active for a few weeks in spring and summer.

Larvae of Photuris, Photinus and Pyractomena genus spend time in the soil, where chemicals filtering down produce potentially disastrous effects on firefly populations. Individuals and park managers should avoid using pesticides (insecticides and herbicides) on lawns and woodlands.

We can enjoy lightning bugs for the first time or again after many years, if we take the initiative to invite them back into our yards, neighborhoods and cities by offering them the habitat they need to survive right alongside our homes. Leave the leaves, turn off the lights, and refrain from regular use of insecticides and herbicides.

Go outside and enjoy the night in late spring and early summer. Chase a firefly and let it alight upon your hand. Look at it closely, watch it glow, and let it fly away into the dark night.

For more information, visit the Xerces Society for Invertebrate Conservation’s Conserving the Jewels of the Night page at xerces.org/endangered-species/fireflies.

Why We No Longer Carry Non-Native Tropical Milkweed

The red and yellow blooms of tropical milkweed are ubiquitous in North Florida butterfly gardens. This non-native milkweed has exploded in popularity as demand for milkweed grows to support declining monarch butterfly populations.  This tropical species, native to Mexico, is very easy to propagate. Growers are able to quickly produce plant material of this species to meet the milkweed demand. It’s also very showy, blooming prolifically all season and regrowing quickly after being decimated by hungry caterpillars. But unlike our native milkweed species, the lush green foliage of tropical milkweed will stay up all winter if not killed back by frost – and that is a problem.

Tropical milkweed has been an invasive species in Central and South Florida for a while now.  The fast growth and prolific re-seeding of this species has remained unchecked by warm winters, resulting in large monocultures of tropical milkweed in natural areas. This replaces native plants and disrupts native ecosystems. But it’s not just the invasive quality of the plant that is damaging.

A protozoan parasite that evolved with monarch butterflies, Ophryocystis elektroscirrha (OE) lives on infected monarchs and is deposited on the plants they land on; especially when the butterflies deposit eggs on the plants. The resulting caterpillars hatch and ingest the OE when they begin eating the plant, and the parasite is able to replicate inside them. Those caterpillars will grow into butterflies infected with an increased load of OE.

Many species across the animal kingdom have evolved with their own particular parasites – humans included. Those parasites are often not too harmful unless they receive some sort of increase in advantage; a weakened immune system or way to accumulate in numbers on its host. Monarchs evolved with OE and are able to prosper while still carrying some of the parasite, but high OE levels in adult monarchs can cause them to fail to emerge from their pupal stage because they are too weak and unable to fully expand their wings. Monarchs with even mild OE infections can appear normal (though are usually a little smaller) but they don’t live as long, cannot fly as well, and are not able to migrate successfully.

In contrast to this tropical species, our native milkweeds naturally senesce in the fall and stay leafless and dormant through the winter. This effectively cleans the plant of the parasite. When the leaves die back, the parasite dies along with them so that when the butterflies return each spring and summer, they feed on fresh, parasite-free foliage. Whereas tropical milkweed, remaining evergreen throughout the winter, allows OE levels to accumulate on the plant. The following generations of monarch caterpillars that feed on those plants can be exposed to dangerous levels of OE.

As our winters have become increasingly warmer in North Florida, we are noticing the invasive potential of tropical milkweed is growing. Warmer winters also mean tropical milkweed is less likely to be killed by frost and more likely to accumulate OE on its leaves. Tropical milkweed can also interfere with monarch migration and reproduction. In northern areas it grows later in the season than native species, and just the presence of tropical milkweed may confuse monarchs into breeding at a time when they should be migrating. There is evidence that suggests the chemical composition of tropical milkweed may trigger this disruption of the innate migration cycle of the monarchs that interact with it – they are fooled into thinking they are in the safe wintering grounds of Mexico. 

With this mounting evidence of the detrimental effects of tropical milkweed, we have decided to only sell native species of milkweed. Unfortunately our growers are still working hard to build supplies of stock to meet demand. Though supplies are limited of native species, we have decided it is better to be without milkweed at some points than to sell a tropical milkweed plant. While it may feed your caterpillars in the short term, it is harmful to the species as a whole in the long term.

Florida has 21 species of native Asclepias, but many are difficult and slow to grow and only a few are well suited for home gardeners. We will continue to work with our growers to provide an increasing variety of native species, but we have found the following species to be the easiest and fastest growing to provide leaf matter for caterpillars:

PINK SWAMP MILKWEED

Asclepias incarnata

A pink-blooming native milkweed that gets big! It grows 4-6ft tall, providing the most amount of caterpillar food (of the native milkweeds) for monarch and queen butterflies. The plants regenerate leaf matter quickly during the growing season and have a short season of bloom in late summer - providing nectar-rich blooms for adult butterflies and other pollinators. They grow best in full sun with moist to wet soils, rich in organic matter. I have found this species to be adaptable in my yard in part sun with average moisture and clay soil amended with compost.

WHITE SWAMP MILKWEED

Asclepias perennis

This free-flowering native milkweed usually only grows 12-24inches tall, continually sending up stalks topped with white blooms that often have a pink blush. They grow best in full sun with moist to wet soils - even growing directly in water! I've found them to be adaptable to quite a bit of shade and also average moisture and clay soils. The leaves provide substantial larval food for monarch and queen butterflies, and the constant flowers attract lots of adult butterflies as well as many other pollinators.

BUTTERFLYWEED

Asclepias tuberosa

One of the most common and noticeable native milkweed species, the clusters of bright orange blooms are often seen on roadsides and grow as far north as Canada. Like many plants with such a large native range, it is important to find plants that are grown from seed sources in your region - this is called an "eco-type". Our plants are North Florida eco-types, so they are well adapted to our hot and humid climate and our soils. Butterflyweed in N. FL tends to be lower growing than it's northern relatives - only 1-2ft tall. It prefers full to part sun and average to dry soils - it can be quite drought tolerant once it has an established root system. I've found these plants to be pretty tough and low-maintenance, and adaptable to sandy or light clay soils. They usually bloom in spring, and then will often rebloom later in the summer.

Welcome Home, Hummingbirds

Indian Pink Spigelia marilandica

We had our first sighting of a Ruby-throated Hummingbird on March 30th this year, a little later than usual. Folks in north Florida usually have the first arrivals from Central America on or about March 15th.  Two excellent plants that provide nectar in early spring are columbine and red buckeye. Both are native to north Florida and do best with some shade. Red buckeye is a small tree with spikes of red tubular flowers. Columbine is a graceful perennial wildflower that has a multitude of red and yellow bell-like flowers.

There are so many great hummingbird plants, it is hard to list just a few. Some wildflowers are red sage, firebush, Indian pink, red swamp mallow and ironweed. Be sure to research planting requirements; for instance, red swamp mallow prefers moist sites.

If you’ve got a sunny arbor or post, plant a coral honeysuckle vine. Give it a light pruning after each bloom period and it will continue to bloom throughout the season. Flowers do not have to be red. Hummers drink readily from silverbell flowers and blueberry flowers, like the Rufous Hummingbird pictured here in Janeen Langley’s yard feeding on native Elliott’s blueberry flowers.

Cupea hybrid ‘Vermillionaire’

Top non-native perennials are red pentas and just about any salvia, from the blue salvias to the maroon and red salvias. The cupheas such as cigarette plant or bat-faced cuphea are fabulous. Most of these will bloom all summer and fall. I also highly recommend planting cardinal guard up close to a window or porch. It blooms in late August until the first frost and is a hummingbird magnet during fall migration.

Most of these plants are planted just outside of our office and living room windows to bring the hummers up close where we can enjoy them. We have so many good hummingbird plants in our yard that we no longer use a hummingbird feeder to entice them.

In addition to plants, you can attract hummers by providing a feeder filled with 4 parts water to one-part sugar. Keep feeders clean and change the solution regularly.

Donna Legare is retired co-founder of Native Nurseries.