10 September 2023
On the evening of Friday 8 September, Marianne Atkinson noticed hundreds of dragonflies patrolling a field near her house in Dubois, PA. Other folks as much as 20 miles away were commenting on the same thing and posting videos online. What were these bugs up to? Marianne sent me her video …
… and this Facebook post from the McKean County Conservation District explaining the phenomenon. Dragonflies are migrating.
The green darner is the most common migratory dragonfly in Pennsylvania but is only one of 16 migratory species in North America. The five main migrants are pictured in the slideshow at top and listed below from Donna L Long’s website.
- Common Green Darner (Anax junius) (photo)
- Variegated Meadowhawk (Sympetrum corruptum) (photo)
- Black Saddlebags (Tramea lacerata) (photo)
- Wandering Glider Dragonfly -or- Global Skimmer (Pantala flavescens) (photo)
- Spot-winged Glider (Pantala hymenaea) (photo)
Green darners have a multi-generational migration. The individuals we see flying south right now will not return but will be the grandparents of those who journey north next spring.
Recent research has indicated that the annual life cycle of green darner (Anax junius) is likely composed of at least three different generations. The first generation emerges in the southern end of its range in early spring and migrates northwards through spring and summer. The second generation emerges in the northern end of its range in summer and migrates southwards in fall. The third generation occurs in the south during the winter and does not migrate.— Wikipedia: Green Darner
When dragonflies migrate during the day in Pennsylvania they follow the same flight paths and fly on the same prime migration days as the hawks. I often see dragonflies at hawk watches where I’m glad they’re eating mosquitos and flying ants on the wing.
Green darners seem to go far but for real long distance the global skimmer wins the prize, migrating from India to Africa across the Indian Ocean! It also occurs in North America.
(video from RoundGlass Sustain on YouTube)
p.s. There are 7,000 species of dragonflies on Earth. Only 25-50 species migrate, making this a very unusual feat.
(photos from Wikimedia Commons, video by Marianne Atkinson and an embed from Youtube)