Q. What has happened to the firefly? They were numerous at one time, but I no longer see them.
A. You’re not alone in thinking so. Lots of folks have been saying that fireflies, or lightning bugs, aren’t as common as they used to be.
Tom Grady, the StarNews’ “Cape Fear Critters” blogger, commented on this back in 2010
This is actually a worldwide concern. It doesn’t take much Googling to find dozens of articles about international conferences on the decline of the firefly.
What’s going on? According to naturalist and WHQR radio commentator Andy Wood, the reasons are pretty complicated, with a lot of interconnected reasons:
1. Pesticide use has clearly cut firefly numbers, although there’s controversy about how much of an effect they have.
2. Development has had some impact, reducing firefly habitats. As Christopher Cratsley, a biology professor at Fitchburg State University in Massachusetts put it, fireflies don’t like suburban lawns.
3. Fireflies like moist soil, so recent drought conditions might have affected their numbers.
4. In the Southeast, fireflies have suffered with the spread of the invasive fire ant. Fire ants love to eat firefly larvae.
5. Light pollution – all the additional street lights and neon advertising signs – might confuse fireflies and interfere with their reproductive cycle.
6. Temporary conditions, such as the cycles of the moon, might also affect firefly appearance, Wood said. Fireflies apparently don’t like to compete with the light of a full or near-full moon.
Fireflies – which technically aren’t flies but belong to the beetle family – are incredibly long-lived for insects, Cratsley noted. Most American species live for at least two years – there are more than 2,000 species of fireflies worldwide, scattered across most tropical and temperate regions – and some Eurasian species live several years.
Most of those lives, however, are spent underground in a larval, or grub form. (Some firefly larvae are bioluminescent, like their parents, and are known as glowworms.) That’s why they like moist, undisturbed soil, preferably in a forest.
Adult fireflies live or 6-8 weeks, using their unique “cool light” – with neither infrared nor ultraviolet radiation – to signal mates. (Most of the fireflies you see are males. Females do light, but their glow is dimmer than the males’ and they stay close to the ground.)
In this area, fireflies usually light up in July, but the recent hot, dry weather might have delayed their debut, Wood said. (He spotted some fireflies early, in June, in parts of New Hanover County.) With recent rains, there might be a strong firefly show in mid-to-late August, Wood said, although appearances might be spotty across the region – heavy in some areas, missing in others.
One of the best things people could do to promote fireflies, Wood said, would be to limit pesticide use.
The Museum of Science in Boston has organized a Firefly Watch, urging local volunteers to report when and where they see fireflies and how many they see. For more information, see: https://www.mos.org/fireflywatch/.
Date posted: August 2, 2012
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