Swarms

What is not good for the swarm is not good for the bees.

~Marcus Aurelius

Earlier this week I was walking down in our woods mid-day, switching out the memory cards in our trail cameras, when I came across a termite emergence near the opossum hole. What I noticed first was a group of large dragonflies, maybe 30 or more, swarming in a sunny patch down by the soon-to-be-dry creek. There were a couple of species of dragonflies, though the larger ones (probably some species of darner) were by far the most abundant. They were zooming back and forth snagging winged termites as they fluttered up from the ground in their nuptial flight. I sat mesmerized for several minutes watching the proficiency of these aerial hunters. I thought I should try to capture some video of this spectacle, but then walked on, figuring I couldn’t capture anything worthwhile with just a phone (boy, was I wrong about that, as you will see later).

I walked about 150 feet along the creek and encountered another, smaller, termite swarm, but with few dragonflies present.

The second termite emergence spot where alates (that’s the caste of winged, reproductive termites in a colony) gathered on a twig tip before taking flight with more on the log below (click photos to enlarge)

I wrote about termite swarms a few years back and pondered then about the triggering mechanism for such synchronous swarms. I found suggestions that temperature (air and/or soil), humidity, conditions before or after storms, etc. as the causes for nearby termite colonies all emerging around the same time. Well, this happened on Tuesday last week, with no significant change in weather before or after that day, so I am still baffled (and in awe) of this phenomenon. After taking a couple of pictures, I continued on up toward the house for lunch.

As I reached our little footbridge, there was another emergence (probably 300 feet from the last one). Interestingly, they were emerging on the same log that I had photographed them on when I wrote that last termite post. When I looked at the photos from that blog post, I saw the date they were taken was May 2, 2015.

Termites emerging on the same log I photographed some on in 2015

The alates followed the same path along the log as they had back then, working their way up toward the tip (the highest point) where most of them took flight.

Here’s a short video clip of the tip of that log and the emerging brood of termites (almost identical to the video clip from 2015).

Termite emergence in our woods last week

As I had found back in 2015, these emergence flights don’t last very long (15-30 minutes), and many predators, both terrestrial (ants, spiders, lizards, etc.) and aerial (dragonflies, birds, bats in the evening, etc.) gather to take advantage of this slowly flying buffet. As this swarm started to thin, I walked up the trail, only to encounter one more emergence. This one was smaller, in deep shade, and had only two dragonflies in attendance. Still, the number of dragonflies I had seen in our woods on this walk was way above any number we normally see, especially down by the creek.

I soon got to the top of the ridge and walked through our side gate to find Melissa out in the yard with her phone making video clips of a cluster (one of the proper collective nouns, although I prefer the more fanciful, dazzle) of dragonflies attacking yet another large termite swarm. There were at least 50 dragonflies (mostly large darners, and we both think they were probably Swamp Darners) swooping to and fro in our side yard out near one the water gardens (this area is basically a small, sunny hole in the forest canopy. I was impressed by the quick clip she showed me and we continued to watch and marvel at the aerial capabilities of the dragonflies as they turned on a dime and snatched a hapless alate out of the air. After a successful snag, a dragonfly would munch in the air (you could see termite wings drop from on occasion) before continuing the hunt, with success after success in grabbing an in-flight meal. Once inside, I was blown away by what Melissa captured on video (and her editing abilities).

So, we present this short video of the amazing airy antics we witnessed (too bad the Oscars are this evening). The first segment is actual speed, but she filmed the rest in slow-motion video. Watch the sharp turns the dragonflies make as they hunt. And keep your eyes on prominent termites as they fly through the screen…do they make it?

Melissa’s iPhone video of a dragonfly swarm feeding on emerging termites in our yard near one of the water gardens and campfire ring (the large stumps)

Once again, we have witnessed synchronous termite swarms in our woods – five swarms over a distance of about 1/4 mile and a time span of about 45 minutes from creek bottom to the top of the ridge. This probably helps with genetic diversity by allowing mates from different colonies to find each other during the short nuptial flights (they drop their wings shortly after landing). But what triggers this synchrony over unknown distances and seemingly varied micro-climates?

And now I have another big question…how the heck do all these dragonflies suddenly appear at these termite emergence sites? We are both amazed that so many dragonflies appeared seemingly out of nowhere (the greatest number of darners I have ever seen patrolling the yard is probably 3 or 4 at any one time). Our friend and researcher at the museum, Chris, has studied dragonfly swarms, and states that this type of swarm is probably a static swarm (feeding swarm), although she speculated these may also be related to migratory swarms (yes, many species of dragonflies migrate). One study showed that the number of dragonflies you see in a swarm is just the tip of the iceberg, with those you count representing fewer than 20% of the number in the vicinity. Where are all these dragonflies on a normal day? Are they cruising the treetops, out of our sight? Can they communicate with one another in some way to take advantage of a short-term food bonanza? I’m hoping Chris sees this and comments with any updates from dragonfly researchers that may shed additional light on how dragonflies can gather so quickly for such ephemeral feeding frenzies. However it happens, it is something special to behold, so be on the lookout for a swarm near you (and have your phone ready).

12 thoughts on “Swarms

  1. Wow, what an amazing display of synchronized behaviors. And Melissa’s video is awesome (Love the music). I wonder if the termite swarms give off pheromones that reinforce the emergence of other nearby colonies. Perhaps those pheromones have been “hacked” by the dragonflies, attracting them to the termite colony.

    • Thanks, Steve. I like that idea of pheromones! And the thought that dragons of the air may have used cyber- (or aroma-) sleuthing to crack the code is awesome. Now to find some corroboration in the scientific literature (or just enjoy watching it next time it happens).

  2. Do you have to have a water source for the dragonflies to be in the area? I’ve seen termite swarms in my city yards but no dragonflies? Melissa did a great job!

    • I agree that Melissa did a great job both shooting and editing the video! As far as water, it probably helps to have potential reproductive sites nearby, but probably isn’t absolutely necessary as I have seen them swarm some distance from known water sources.

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