Why you don’t see fireflies in the Northwest | KUOW News and Information

Why you don’t see fireflies in the Northwest

Aug 31, 2017

"Where are all the mosquitos and fireflies?" 

KUOW listener Tom Miller, originally from Minnesota, had that question for our Local Wonder team. 

University of Washington entomology professor Patrick Tobin came into the studio to answer that question. He spoke with host Bill Radke on The Record.

First, the lack of mosquitos (not that we’re complaining):

We get our rainy season in the fall and winter, Tobin said, which is not a good time for insects to reproduce. And even though we're surrounded by water, it tends to be moving, too deep, or too cool.

The result is fewer generations of bugs. For instance, Tobin said Florida mosquitos can go from egg to adult in seven days (terrifying). But with our lower temperatures, it could take a month.

Know what does make for a great mosquito habitat in urban environments? Bird baths.

Okay, so where are the fireflies?

We have them! But ours don't produce light.

Radke: “Wait a minute, a firefly that doesn’t produce light? Isn’t that the one qualifying feature to be a  firefly?”

Tobin: “You would think so, but they’re also not flies; they’re actually beetles.”

There are more than 2,000 species of fireflies/lightning bugs/whatchamacallits. The ones that do produce light are using this tool to find a mate. Ours in Seattle are daytime fliers or use other cues to find a mate.

“The species we have here have not evolved that strategy,” Tobin said.

So we don’t have the dramatic nocturnal shows in the Northwest, but fireflies are also on the decline in the east. One reason is habitat loss. But another big cause is light pollution.

Tobin: “They’re flashing to find a mate, and if light pollution is interfering with the ability for a male or female to see that flash pattern, they don’t find each other.”

Radke: “They’re crying out for company and their mates can’t see the light? That’s the saddest thing I’ve ever heard!”

(This might work out for some. Tobin said there is a species of “femme fatale fireflies” that flashes with the sole purpose of luring in a male to eat.)

Tobin said bugs that don't depend on flashing light could benefit them here in Seattle, which has a fair bit of light pollution.  

Produced for the web by Kara McDermott.