Rebjane63 on Nostr: Credit: Gardening Tips and Tricks (Facebook) "One of the most surprising migration ...

Credit: Gardening Tips and Tricks (Facebook)
"One of the most surprising migration stories in North America involves an insect people assume never leaves the pond.
THE SPECIES: Common green darner (Anax junius) — one of the largest and most widespread dragonflies in North America. Bright green thorax, blue or purplish abdomen in males.
THE MIGRATION: Research using stable isotope analysis (led by researchers including Michael Hallworth at the Smithsonian Migratory Bird Center) showed green darners complete a multi-generational migratory cycle. One generation moves north in spring, a subsequent generation moves south in fall, and a resident generation overwinters in the south — a relay strategy similar in structure to monarchs.
THE DISTANCE: Individual dragonflies have been documented traveling hundreds of miles, with the full annual cycle spanning a far greater range.
THE SWARMS: Large fall movements sometimes produce dramatic swarms along coastlines, lake shores, and ridgelines — occasionally dense enough to show up on weather radar.
WHAT TRIGGERS IT: Migration is linked to temperature thresholds — cold fronts push southbound movement.
WHY IT MATTERS: Migrating dragonflies are voracious predators of flying insects, including mosquitoes, and they in turn become critical fuel for migrating falcons and other raptors. American kestrels and merlins are frequently observed hunting migrating dragonflies.
WATCH FOR IT: Clear day after a cold front, near open water or along a shoreline, September. Look for hundreds of large dragonflies all moving the same direction."
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