Missouri has a number of firefly species (beetles in family Lampyridae). The adults of most species are readily identified by their brown or black, soft bodies, somewhat leathery forewings, and a usually red or orange pronotum (a shieldlike plate) that covers the head from above. The last few segments of the abdomen are pale yellow and can glow yellow, green, or sometimes orangish yellow, or amber, depending on the genus and species. They are Missouri's only flying, bioluminescent insects.
The larvae, called glowworms, are wingless, flattened, segmented insects with a series of plates covering the body. They don’t blink, but they do glow continuously and can be seen on the ground, especially in moist areas near grass and brush.
Length: to about ¾ inch.
Statewide. Different species may have different distributions within the state.
Habitat and Conservation
These beetles are nocturnal and crepuscular (active at dawn and dusk). They are usually seen in spring and summer, when the winged adults fly, winking their bioluminescent abdomen tips. They’re commonly seen in pastures and old fields, yards, edges of forests, and around streams.
The larvae are most common in damp or moist places, such as lowlands, wetlands, damp pastures, and near ponds, lakes, and streams. Some larvae are aquatic.
If you want to encourage fireflies in your area, avoid using broad-spectrum insecticides.
See the Status section for conservation issues concerning fireflies.
Food
The larvae are voracious predators with jaws equipped with toxin to help them overpower snails, slugs, earthworms, and other soft-bodied prey.
Adults eat a variety of foods, depending on the species.
In some firefly species, notably members of genus Photuris, the predatory females mimic the courtship flash patterns of other fireflies (especially those in genus Photinus). In this way, the Photuris females lure in unwitting Photinus males and then eat them.
Status
Common throughout the state. Some species are more common than others.
Globally, firefly populations have shown evidence of decline, due to habitat loss and degradation and the related issue of climate change. Like many other organisms, fireflies require habitats that are large enough to support a healthy population, but they also need nearby connected, not isolated habitats. In this way, a disaster that destroys a population in one locality can be repopulated by fireflies in a neighboring (connected) area.
Insecticides and herbicides can also cause declines, as they reduce firefly numbers directly but also reduce the amount and types of potential prey insects.
Light pollution is also a concern for firefly conservation, because these insects must use their nighttime light signals to find mates. Without a dark enough night, their light signals are lost, hindering their courtship and mating.
Life Cycle
These beetles overwinter as larvae, and in spring they metamorphose into adults.
The flashes and accompanying movements are used for courtship. The different species have their own precise rhythms, flashes, and movements. Some species lack bioluminescence altogether.
Human Connections
The larvae help control snails and slugs, which are banes to the gardener.
The flashing adults are endlessly entertaining to children and adults. Their quiet presence adds to the magic of a Missouri summer night. It's one of the true wonders of nature to see thousands of fireflies winking all across a low fallow field, or, if you're lucky enough, to see an entire group of fireflies in a stream valley winking on and off in unison. In our area, try looking for this phenomenon starting in early June.
Conservation is a human responsibility. As with most other organisms, habitat preservation a central key to maintaining healthy populations of the various firefly species. See the Status section to learn about some of their conservation issues.
Many scientists use luciferase (the bioluminescent enzyme) in gene research, as a way to observe biochemical processes, and in forensic research (including crime scene analysis).
Old-time Ozark tradition held that the appearance of fireflies meant that cold weather was over and it was safe to set out tomato plants.
For centuries, the Japanese people have made a point of firefly viewing during the summer. There are several parks, mostly in rural areas without much soil, water, and light pollution, where people go to enjoy watching fireflies and reflect on their beauty, nostalgia, and mystery. In some cases, natural populations of fireflies are enhanced by breeding programs, and people hold festivals celebrating the appearance of these amazing insects.
The most typical species of Japanese fireflies have their own common names, including the Heike firefly (heike-botaru, species Aquatica lateralis) and the Genji firefly (genji-botaru, species Nipponoluciola cruciata). None of the approximately 175 US or Canadian firefly species have widely recognized common names.
There are many references to fireflies in Japanese culture. As early as the eighth century, Japanese poets used them as a symbol for passion and the change from spring into summer. A Japanese folk tale tells how the souls of fallen samurai turned into fireflies. Many artworks depict them, ranging from valuable antique paintings and woodblock prints to recent anime films.
Ecosystem Connections
The larvae help control populations of the various invertebrates they prey on. The larvae and the adults are rarely eaten by predators, as they contain chemicals that make them distasteful or toxic.
Occasionally, an entire group of fireflies in a location (often in a low area like a creek bed) will blink in unison. It is a spectacular sight, and scientists aren't quite sure why or how it happens.
Entomologists who study fireflies have learned to separate species based on flash patterns, just as the beetles themselves distinguish among one another with flash patterns during courtship. In many cases, fireflies that are virtually indistinguishable in body form are quite different in flash pattern. Look for these different patterns as you watch fireflies: some fly in a straight line, flashing in a dash-dash-dash pattern; others swoop in illuminated J shapes, and so on.
Many fireflies are equipped with chemicals that make their bodies distasteful to predators such as birds and spiders. Members of genus Photinus are some of the species that have these bad-tasting chemicals. One reason why female Photuris fireflies eat male Photinus species is that by consuming them, they not only obtain nutrients but also acquire the icky-tasting chemicals for themselves.
What explains the steady glowing of firefly larvae? They are too young to be attracting mates. It appears that their glowing is a warning to potential predators: a bright, unforgettable color that predators learn to associate with toxic or bad-tasting prey. (Examples of similar warnings include the orange and black pattern of the monarch butterfly, the bright red of milkweed bugs, the black and white stripes of skunks, and the yellow and black stripes of bees and wasps.) Apparently, fireflies developed the adult behavior of flashing courtship signals after the establishment of the larval warning of toxicity.
There are about 175 species, in about 20 genera, in North America north of Mexico. Globally, this family comprises at least 2,200 species in about 140 genera, but experts estimate that thousands of species remain undescribed by science. One reason they are difficult to study is that, in many cases, species can only be distinguished by flash patterns.
