Food Chain

Paddle-tailed darners, Aeshna palmata

Terry Domico

It had been a warm July on the San Juan Islands, I remember thinking while considering an afternoon swim at Sportsman Lake. Then a vague commotion on the far side of the yard caught my attention. A hundred or more large dragonflies swooped in a tight circle, a circle that extended sixteen feet across and levitated several feet above the ground. At first look, the swarm reminded me of a WWI biplane dogfight.

I’d never before seen such a densely packed aggregation of dragonflies. These were paddle-tailed darners (Aeshna palmata), a species of large dragonfly named after the two paddle-shaped mating appendages on the tip of the abdomen. Sitting down on a nearby bench, I soon realized what had attracted them: termites. Winged western drywood termites, Incisitermes minor, were emerging en masse from a rotted tree stump. Virgin queen and king termites covered the old stump in a shimmering frenzy for their one and only nuptial flight.

The matings were not to be. As fast as the termites became airborne, the dragonflies deftly plucked them from the air. All of the hopeful couples that I watched were nabbed before they got any more than eight feet away from their launch point. Within a few minutes’ time, hundreds of termites had been intercepted, and the horde of darting dragonflies appeared to have doubled in number. Was word of a feeding event somehow getting out to the others in the neighboorhood?

Soon a squadron of aggressive yellowjackets (Vespula spp.) arrived on the scene. Boldly, the papermaking wasps dove headfirst into the seething mass of winged termites, usually emerging with the thorax or abdomen of a termite, neatly trimmed of its wings and legs. One of the raiders emerged with an entire termite in its jaws. Now and then, in the melee, a wing would disarticulate and begin drifting towards the ground, as delicately light as thistledown

The family cat, Zeena, broke the spell. She jumped into my lap, wanting to have her ears rubbed, until the battalion of dragonflies caught her attention. In a flash she was back on the ground. Her head twisted this way and that as she attempted to follow their quick movements. Every now and then she leapt, raking the air with her forepaws. A blur of fur and suddenly the cat had one of the dragonflies on the ground. It was a big male, fully three inches long with a wingspan of almost four inches. A lucky grab. Zeena played with it for a few moments and then turned her attention skyward again. In two more attempts she nabbed another one. She was getting good at this game. Time to stop her and spare the rest of the dragonflies.

I picked up the cat and her mangled prey and sat back down on the wooden bench. Something had changed, however. There were fewer dragonflies in the air, and the termites were retreating into their subterranean nest. Ten minutes later the show was over, with only a lone dragonfly patrolling the area. I got up and slowly carried my purring feline back to the house. I had completely forgotten about going for a swim.--TD

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