Anita’s Blog — Signs of Autumn

Amazingly, summer noticeably turned into fall here in the Deep South of Texas for a couple of days.

This short cold front gave us a fall-like respite for tending to outdoor chores. Most notably making yard work fun again on our small squiredom are the legions of dragonflies. Hundreds of them are flying over the neighboring pasture outside my windows as I write this. During the week, they appeared in choreographed contingents like aerial water ballets in different sections of the yard. I found it impossible to photographically capture the spinning myriads in all their glory. It was more successful to follow when one broke ranks and alighted on a twig.

Dragonflies perch on almost anything and rest — often and at length — it’s a time for them to recharge their body and brain. If you wish to study them, the best approach is directly behind, where their vision does not extend. Nearly all of a dragonfly’s head consists of two huge compound eyes that give it nearly 360-degree vision.

A quick glance of a resting dragonfly tells whether you’re looking at a dragonfly or damselfly. The abdomen of a dragonfly is thicker than the slim one of a damselfly. The eyes of damselflies are widely separated. They close their wings above their abdomen when perched.

Dragonflies rest with their wings spread; their eyes touch near the top of their head.

I fell in love with dragonflies about the same time I discovered (and fell in love with) helicopters — at about age seven — remember the Whirlybirds television show? Truth be known, I always thought dragonflies and helicopters were somewhat similar — if you consider a dragonfly’s wing anatomy to be more intricate than the main rotor mechanism of say, a Sikorsky UH-60 Blackhawk helicopter. You decide — check out the next two photos:

I say more intricate because dragonflies can move each of their four wings independently which is awesome in itself and not something helicopters can do — yet. That independent movement capability allows a dragonfly to flap up and down and rotate forward and backward. Dragonflies can fly up, down, backwards, sideways, hover like a helicopter and make hairpin turns in the blinking of an eye.

All this maneuverability makes for some pretty exciting swarm shows to watch while sitting atop a mower. Hundreds of dragonflies of different species can gather in this type of opportunistic feeding swarm. My visual guestimate of one such lawn-mowing-induced dance was about 30 individual dragonflies and with no guess as to how many different species. In reality, their antics were not dissimilar to seeing a swoop of swallows creatively dancing a tango over the resaca as they feast on airborne insects.

Speculatively, it was no different than mockingbirds and grackles pouncing and grabbing insects from the grass after a pass with the mower. I wondered if the mower was perhaps stirring up mosquitoes — a dragonfly’s favorite food — and that that was the general cause of the gyrating masses.

A single dragonfly can eat hundreds of mosquitoes a day. They catch their insect prey by grabbing it with their feet and making a basket so the prey can’t escape. Dragonflies also eat flies, gnats, even butterflies and smaller dragonflies.

I found a reference agreeing that small insects living in grass would be disturbed by activity such as a lawn mower, which in turn would cause insects to fly around more than they usually would — the prey then draws in the dragonflies and swarms form. The article also suggested that dragonflies have learned to follow large, slow-moving objects such as people, bicycles, cows and cars because they disturb prey insects as they move and encourage the prey to fly. https://thedragonflywoman.com/2010/09/22/staticswarms/

Dragonflies belong to the order, Odonata. They are found on every continent except Antarctica. There are more than 7,000 species of dragonflies, 450 species in the U.S. and Canada and 238 species in Texas — which is more than in any other state. According to fossil records, dragonflies have existed for more than 300 million years, and back in the day, they had a two-foot wing span, possibly, according to some theories, because the percentage of oxygen in the air was higher, which allowed insects to be larger.

Dragonflies — darners, skimmers, pondhawks, amberwings, dashers, saddlebags, emeralds — there are so many I had to forego being able to name them and just be happy to celebrate their abundance as I toil in their habitat — besides, the experts have a nice check list of Texas Odonata at the following link:

https://www.inaturalist.org/check_lists/67614-Odonata-of-Texas