Bug Day (4): Meadowhawk
Birds aren’t the only creatures that migrate. They aren’t the most numerous, and their collective biomass is second to another order entirely: migratory insects. The most well known migrating insect locally is the Monarch butterfly. Less well known, but very prominent among migrating insects are the dragonflies, and a star migratory dragonfly is this Variegated Meadowhawk. It has strong, stiff wings that can propel it where it wants to go, given a favorable wind. It can even refuel in flight by snatching up mosquitoes and other airborne insects. At least nine species of dragonfly travel through our Bay Area in autumn. Citizen scientists who normally observe raptors take a break in the fall to count meadowhawks. Exactly where the bugs start their migration and where they end up remains fuzzy. GPS trackers haven’t got quite small and cheap enough to attach to dragonflies, so it falls to amateurs with cameras to spot and report their sightings.
The one in the photo above is probably a female. Adult males tend to be red or reddish. Like other dragonflies, the meadowhawk is carnivorous. It’s a hunter, killing and feeding on other insects, sometimes of its own species.
Dragonfly reproduction is a complicated matter. During mating, the male uses prongs at the end of his tail to grasp the female at the back of her head, and the female then curls her abdomen under her body to pick up sperm from the male’s secondary genitalia at the front of his abdomen, forming a unique and somewhat bizarre “heart” or “wheel” posture. Once the male has deposited his sperm (frequently after scraping out and dumping the sperm of his mate’s previous partners), the female lets go, but the male keeps his grip on her head, and together they fly over the surface of the water where the female drops her newly fertilized eggs.
For a beautifully done feature-length video introduction to dragonflies generally, check out Sky Hunters on YouTube. For a short video of meadowhawks locked together in flight to lay eggs, try this. Our Bay Nature magazine ran an excellent piece on meadowhawk migration in 2017 by local science writer Claire Peaslee. The Odonata Central website carries meadowhawk and other dragonfly observations. There’s more information on the Migratory Dragonfly Partnership site. And, of course, there’s Wikipedia, which kind of falls down on this topic. Late addition: Wonderful post about dragonflies, including this one, by Tara McIntire in the Golden Gate Audubon blog.