MISSING FIREFLIES

Iconic pieces of a summer evening in Maine: a late humid sunset, a distant yodel of a common loon, the flickering of fireflies. But the latter – as quite a few people have noted and written in to ask about – is unfortunately becoming less common. It should come as no surprise that they’re decreasing – especially with recent stories telling of an “insect apocalypse” – but with so many people asking “where are the fireflies?” it seems like an easy topic to cover here, especially because there are things we can all do to help.

First, it helps to know what fireflies are up to. Fireflies, also known as lightning bugs, are insects, specifically beetles (Coleoptera) and not flies (Diptera). Fireflies are able to produce light, a process known as bioluminescence, thanks to a chemical mixture in their abdomens. They use this as a form of communication, particularly for mating. The male fireflies will fly around in the evening, flashing their lights, as females watch from the ground. When a female sees a flash that she likes (one from her own species), then she’ll flash back, the male will fly down, and they’ll mate.

So one of the most important things, if you are a mating firefly, is to have darkness. Unfortunately, darkness is becoming less common. Studies show that light pollution increases around 6% annually in North America, often coming from floodlights, street lights, and advertisements or display lighting. Where there is increased light pollution, there is a decline in fireflies, simply because they can’t effectively communicate.

This doesn’t mean we need to get rid of all outdoor lights, especially since many of them are there for safety reasons. Start with being mindful about what lights you have on, especially wide-casting floodlights at night, and consider shutting them off when they aren’t in use. Even changing the type of fixture can make a huge difference. Use fixtures that direct light downward with shields, or look for ones called “full cutoff,” with no light emitted above horizontal. Those are both great ways to limit or cut back on light pollution.

The other important thing to change in order to help fireflies is our use of pesticides. Again, I want to acknowledge the safety concern here, as many people are worried about ticks and other biting insects, but it is important to realize that pesticides and insecticides will likely impact much more than just those “problem” insects. If you are treating your yard for mosquitoes, you shouldn’t be surprised when you don’t see fireflies.

One thing I learned recently is that firefly larvae love to eat slugs. More research needs to be done, but there is a correlation between areas that see a decrease in fireflies also seeing an increase in slugs. Interestingly, I often receive calls from people asking about how to control slugs in their gardens, for which there are plenty of safe and organic products to use. The active ingredient in many slug controls is acephate, which is a non-selective insecticide that will kill any insect that comes in contact with it. So instead of reaching for that “solution,” perhaps shutting your lights off, maybe letting the grass grow a little longer, and leaving fireflies to do their thing will be the solution you need.

SONGBIRDS AT NIGHT

It’s actually already time to say goodbye to summer. It ends especially early if you are a bird, as evidenced by the southbound shorebirds we saw passing by on their fall migration a few weeks ago. They’ve got a long way to go, so they can’t waste any time, but for some songbirds breeding in Maine, they’ll try to sneak in every last bit of summer that they can. Though nesting season wrapped up for most birds, some of them are still giving it the college try. This led Susan and Jim Kanak of Wells to write and ask about birds they hear singing at night, waking them up at 1 a.m.

The likely singer, especially in southern Maine, would be a northern mockingbird. Some species, like American robins, are remarkably early singers and often start well before twilight. The mockingbirds, however, are known to sing their nocturnal songs for a particular reason: They’re trying to lure a neighbor’s mate. We define songs as noises (mechanical or vocal) that are used to attract a mate or defend a territory, and mockingbirds singing late at night are known to be unpaired males. Desperate times call for desperate measures, but at least it isn’t John Cusack blasting Peter Gabriel’s “In Your Eyes.”

The other cool nocturnal songs you’re likely to hear are coming from two warblers. Both common yellowthroats and ovenbirds have complex songs, done as part of an aerial display, that they’ll perform at night. Instead of the yellowthroat’s “witchity – witchity – witchity” or the ovenbird’s “teacher – teaCHER – TEACHER,” they tend to sprinkle in a jumble of additional notes on either side of the song. It makes you wonder why they have the variation, but perhaps the extra effort is what it takes to find a mate, and in the cover of darkness you don’t have to worry about predators as much. It isn’t hard to anthropomorphize the birds and sympathize with the situation: it’s getting late (end of the breeding season), the band is playing its last song (sing your complex song), and maybe a funny dance will help find a mate.

Do you have questions or topics for Doug that you would like him to address in future columns? Email ask@maineaudubon.org and visit maineaudubon.org to learn more about backyard birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug leads free bird walks on Thursday mornings, 7 to 9 am, at the Gilsland Farm Audubon Sanctuary in Falmouth.

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