When was your last time to see lightening bugs?We call them lightening bugs. Others call them fireflies, but all of us have great childhood memories of watching them swirl around the yard at dusk, creating trails of blinking light, while we ran around trying to capture them in a glass jar.
About 170 firefly species live in the U.S. Worldwide over 1,900 species exist. Texas has 36 species. Most fireflies are not described by a common name, as they are hard to identify separately, and many look alike. They are referred to by the family grouping to which they belong. These three are common in the U.S. – Photinus, Photuris, and Pyractomena.
Why should we care? Well, it’s interesting because the Photuris female will imitate a Photinus female to lure a male of that species to his doom, as she will pounce on him and eat him.
Fireflies are actually beetles. The fireflies we see at night are nocturnal, and sleep during the day in bushes or in leaves on low hanging branches. And, no, they do not glow while they sleep.
Other firefly species are active during the daytime and do not produce light. In order to attract a mate, the daytime fireflies emit pheromes.
Fireflies use their lanterns, the light-emitting organ, to attract a mate and to warn predators. Each firefly species has it’s own flashing pattern that can be used to distinguish between species, as several types of fireflies usually occupy the same habitat. Flash colors are different between species, too. Some flash a light, neon green, while others emit a reddish yellow light. Usually, the fireflies that have the green light come out later in the evening. All fireflies need some light to see, as they will run into things in the dark.
Spiders, bats, and toads like to eat fireflies. This can sometimes be dangerous, as fireflies have a chemical in their blood that makes them taste bad, and can sometimes even be deadly to creatures that try to eat them.
Springtime is mating season. The males fly flash patterns to attract a female, who perches nearby watching. If she likes what she sees, she flashes back. Females are looking for the male with the brightest flash and the largest “nuptial gift.” The “nuptial gift” is sperm to fertilize the eggs and food to feed them. She lays about five hundred eggs on the ground, where they hatch in about a month. What’s cool is that the eggs and larvae of nocturnal fireflies glow.
The larvae, called glowworms, are predatory and eat small insects, slugs, snails, and earthworms. They inject their prey with toxic digestive enzymes before sucking out the liquefied body contents.
The larvae spend the winter in the soil. As adults, which takes about two years to occur, fireflies will eat pollen and nectar. There are actually some species that don’t appear to feed once they become adults.
The firefly’s lantern uses two layers of cells to make light. One is a reflector and the other a light producer. Firefly light gives off very little heat, and is produced very efficiently. Two substances are used to make it; luciferin and the enzyme luciferase.
These two chemicals are currently used in medical research in cystic fibrosis, multiple sclerosis, and heart disease. Doctors also use them to detect within patients whether cancer treatments are working.
The Museum of Science in Boston has a Firefly Watch, where it is asking citizen scientists to monitor and record firefly sightings online. Here is the link if you are interested: https://www.mos.org/fireflywatch/ about_firefly_watch.
El Camino Real Master Naturalists: