Environmental Factors

Why We Ask About The Details

There is much that we still don't know about what ecological and human-made factors affect firefly populations. The data you collect for Firefly Watch can help our researchers gain a better understanding of how the following elements influence the fireflies in your neighborhood.


To be most useful, a habitat site should be fairly small and cohesive. It should be no larger than the area you can see easily while standing in one spot. A backyard that includes shrubs and trees can be considered one habitat, but a pasture bordering that yard would be considered a different habitat.

Lawn Care


During the day, fireflies can spend a lot of time on the ground and may be susceptible to frequent mowing.


Researchers don't know what effect fertilizers have on fireflies. Many fertilizers contain both weed killers and pesticides.

Weed killers

We don't know what effect weed killers (herbicides) have on fireflies.


People apply pesticides to control insect pests, but pesticides also kill many non-pest insects. Firefly larvae — young fireflies — are not pests, but they are grubs that live in the soil and will come in contact with lawn pesticides, which target grubs.

Adult fireflies may come in contact with sprayed pesticides, some of which are used on localized problem areas like trees. Others, like those targeting mosquitoes, are sprayed over a large area. Although it may seem reasonable to assume that pesticides have an adverse effect on firefly populations, we need data to prove or disprove this assumption.

Light Sources

House or Building Lights

Most fireflies find a mate by flashing. They must be able to see the flash of a prospective mate and return the flash. We don't know to what degree outside lights affect a firefly's ability to locate a mate.


Streetlights produce a type of light different from house lights, and we'd like to determine if one type of light is more detrimental than the other.

Nearby Water Sources

Firefly larvae live in the soil, and they need a certain amount of moisture to survive. In some areas, rainfall and shade may be enough to keep the soil moist. In others, the moisture may come from standing water, but we don't know how important standing water is to fireflies' survival, nor do we know how different types of water affect them.

When you join Firefly Watch, you're not only tracking firefly sightings in your yard; you're also helping local scientists with their research.
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Observing fireflies is a great summer activity. Join our network of volunteers and track your sightings throughout the season.
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Pick a location, observe it weekly, and use our online tools to follow your progress.
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Wear bug spray to protect yourself from mosquitoes, but take caution if you're handling fireflies.

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