Newswise — For many people, fireflies lighting up backyards is a sign of summertime. The thrill of catching them in a jar and releasing them back into the wild is a childhood pastime. But if you have noticed a decline in fireflies over the years, you’re not alone. Virginia Tech entomologist Eric Day explains why climate and urban development are playing a big role in the decreasing numbers. 

“Fireflies can be seen, depending on location, starting in late April through October, but they are most active in late May and early June,” said Day. “Where you see them all depends on location. Old hay fields near creeks will have normal populations, but highly manicured lawns rarely have fireflies.” 

Day said that housing and commercial development are the biggest threats to firefly habitat loss. This includes artificial lighting. “This is why we’re seeing less and less each year. The more development there is, the less room there is for them to thrive.”

These insects thrive in temperate weather with wet, warm summers and cold winters. “Rising temperatures and changes in precipitation are impacting their numbers,” said Day. 

The term extinction has been thrown around a lot due to their dwindling numbers, but Day said he wouldn’t use that term specifically. “I would say fireflies are threatened due to habitat loss, but they are not going extinct, some are adapting in different regions.”

To keep fireflies around, Day recommends that homeowners stop spraying their yards with pesticides and herbicides, tolerate weeds, and mow less. “The presence of fireflies indicates a diverse habitat and doing these things is essential to ensuring future generations are able to enjoy the natural wonder of skies lit up by them.”

About Day

Eric Day is the manager of the Insect ID Lab in the Department of Entomology at Virginia Tech. His areas of expertise include insect identification and pest surveys.

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