To the rescue of fireflies

Last week I talked about the possibility that fireflies are on a decline in our area. I promised to revisit the subject this week and talk about what can be done to help preserve habitat and conditions favorable to these flashy beetles.

I found the most concise, helpful information at a website simply called “Firefly” (http://www.firefly.org/firefly-habitat.html). The site lists habitat requirements and actions for helping fireflies thrive. Here’s what I learned.

Whether a firefly species lives in the forest, in fields, the edges between them, or in dry-ish climates, all fireflies need standing water. It doesn’t have to be a lot of water; a low area that holds the spring rains long enough during mating season will suffice.

If you don’t love the hot, humid weather that is typical of the Delaware Valley, it may help to know that fireflies love this environment. In fact, though fireflies are found pretty much everywhere around the world, the greatest diversity of species is found in more tropical areas.

What surprised me is that scientists “aren’t completely sure” what fireflies eat. The larvae are “believed to be carnivorous, living off smaller insects, snails, and slugs.” Adult fireflies eat pollen and plants, and “may also live on other insects.” Some species don’t eat at all, living only long enough to mate.

Fireflies love long grass. After spending the day on or near the ground, at night they crawl to the tops of blades of grass and from there fly up into the tree canopy. This brings us to one of the possible reasons why fireflies are declining: over-mowing our lawns.

According to Firefly and other websites, while researchers are not entirely sure why firefly populations are declining, they cite development (no surprise there), and also light pollution as the chief causes. Open fields and forests, which make ideal firefly habitat, are continually being encroached upon. The more that open spaces are built on, paved over, and neatened up, the less rotting wood and forest litter there is for firefly larvae to live. “Logging, pollution, and increased use of pesticides” may also contribute to the decline. It also appears that plain old human traffic disrupts habitat as well.

Finally, there is the problem of lights at night. When you’re a nocturnal insect that relies on you and your potential mates being able to see each other’s flashing light, competition from streetlights, shopping centers, porch lights, and car headlights can be a problem. The sad truth is that, “Where fireflies once had uninterrupted forests and fields to live and mate, homes with landscaped lawns and lots of exterior lights are taking over,” states www.firefly.org,

Apparently, it’s only in the past several years that scientists have turned their attention to fireflies, so there isn’t clear evidence yet that the following actions will have a positive effect on fireflies, but they sound like good ideas for the environment in general.

Turn off outside lights at night — and even draw the curtains and shut the blinds to prevent interior light from shining out.

Let fallen logs and leaf litter accumulate — where you can. It doesn’t have to be a lot.

Create a water feature in your landscape — a chlorinated swimming pool doesn’t count.

Avoid use of pesticides — especially lawn chemicals. Indirect evidence indicates that lawn chemicals are toxic to insects where firefly larvae are found, and are toxic to the food that sustains firefly larvae.

Finally, check out the Boston Museum of Science “Firefly Watch” project. The museum has teamed up with researchers from Tufts University and Fitchburg State College to track the fate of these insects. With the help of “citizen scientists,” they hope to learn about the geographic distribution of fireflies and their activity during the summer season. (Go to https://legacy.mos.org/fireflywatch/about_firefly_watch)