Warm, humid weather fuels firefly mating spectacle across Germany

Ideal weather for a glowing spectacle

The recent hot days and intermittent rain showers have created ideal conditions for fireflies across Germany. Helge May from the Naturschutzbund (NABU) said the warm, humid weather benefits the beetles, as long as evening thunderstorms do not disrupt their flight time. "At least so far, we can assume it's a good firefly year," May noted. The greenish blinking is currently visible in many gardens and along roadsides.

How fireflies produce their light

Fireflies generate light through bioluminescence, a reaction involving the enzyme luciferase and the compound luciferin. Unlike a flame, this process produces almost no heat. The light organ sits on the underside of the abdomen, where the chitin shell is thin and translucent. The glow serves reproduction: flightless females sit on the ground or elevated perches and emit light to attract flying males. In the Small Firefly species, both sexes glow; the floating points of light are males.

When and where to watch

The best observation window runs from about 10 p.m. to midnight, with the season peaking around the summer solstice and lasting into early July. NABU recommends warm, windless, and dark nights, especially around the new moon. In Lower Saxony, local NABU groups offer guided walks in towns such as Barsinghausen-Egestorf, Rinteln, Bad Münder, and Wennigsen.

Usually only five to ten days, from mid-June to early July, they fly out at dusk and go on bridal search.

When it glows eerily in the air, those are always males of the Small Firefly.

Why gardeners welcome fireflies

Firefly larvae are voracious predators of slugs. They follow the slime trail, sink their jaws into the slug, and inject a paralyzing, pre-digestive fluid. Gardeners plagued by snails can encourage fireflies by leaving unmowed grass strips, creating brush and leaf piles, and avoiding chemical slug pellets, which also kill the larvae. The Bavarian conservation group LBV advises planting native deciduous trees and shrubs, adding a pond or tall perennial bed, and turning off nighttime garden lights.

Threats and conservation

Native firefly species are not currently considered endangered nationwide, but they face growing pressure from habitat loss, frequent mowing, pesticides, and light pollution. Artificial lighting makes it harder for males and females to find each other. NABU urges gardeners to reduce outdoor lighting and preserve woody structures near water. The adult phase is brief: after three years as larvae, the beetles live only five to ten days, mate, lay eggs, and die.