Dragonflies crowding Chicagoland on their way South

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CHICAGO -- If you haven't noticed already, you will notice very soon that dragonflies abound in the Chicago area. The great migration is underway and gaining steam through September.

Chicago is merely a pit stop this summer as the bugs head South this time of year.

Dragonflies are harmless to humans but can swarm as they travel in groups of a thousand or more.

Dragonflies flock to bodies of water to feed on other flying insects.

"Dragonflies are a necessary part of the food chain simply because they are such efficient predators. Without dragonflies, we would undoubtedly have great numbers of nuisance insects,” says Peggy Notebaert Nature Museum’s Doug Taron.

Nuisance insects like mosquitos. While these lightweight, fast-moving, seasonal insects alone can't control the mosquito population, they help manage it.

"Dragonflies are just one part of the bigger picture that helps keep nature in balance,” Taron says.

Last year, dragonflies descended upon the Chicago area in enormous numbers. The Green Darners species are a hearty stock and can live 6-7 months before dying off. Other, more rare species, have a much shorter lifespan. Water quality influences their survival rate.

But none of them bite or sting.

That's what scientists do know. There are still many unknowns, however, when it comes to dragonflies.

"We don't really know much about the migration yet,” Taron says. “For example, we don't know where they go when they migrate. … We know they fly south this time of year, but where they end up is still not really clear.”
Trackers suspect they head to the Gulf Coast and perhaps New Mexico.

"The lesson from dragonflies is that there's a real range from species even in the same groups and how they respond to changes in the environment,” says Taron. “They show some of the hope and concerns about the environmental changes."