Nuptial Flight
We usually think of ant nests as complex, underground structures containing various tunnels and chambers where food is stored, young are cared for, and eggs are laid. This is indeed what the domestic life of many species looks like, but it is far from universal. Some ants build their nests in existing structures, like dead trees or old buildings; others will simply gather beneath a log or rock in the woods.
I've been flipping over a lot of logs and rocks this summer while doing salamander surveys and so I've run into a lot of these more minimalist ant nests. Usually, what I find is a bunch of regular looking worker ants and the tiny, cylindrical, white larva that they look after. When I take the roof off of their house, the workers scramble, some gently picking up the larva in their mandibles and moving them to a safer location, and others running out to try and bit my hands.
More recently, however, I've been seeing some other, rather strange looking insects hanging around these nests. The insects look like ants - they are usually either black or reddish in color, with three very distinct body segments - except for one key feature: these insects have wings. Like, actual wings that they can use to fly around. What are these bugs and what are doing in the ant nests?
The answer came last week when, on a hot, humid evening, I set out a bunch of insect light traps in a field near where I've been looking for salamanders. These traps are basically just what they sound like - they use light to attract flying, nocturnal insects, then corral them down a funnel and into a sample cup. I've set these traps a few times this summer as part of a project looking at bat diets, so when I went to bed that night, I was excepting to wake up the next morning and find sample cups full of the same insects I'd been catching - mostly moths, beetles, caddisflies, and mayflies.
I did indeed get plenty of these insects when I checked the traps early the next morning, but that wasn't all. In addition to the all the usual suspects, I found that each of the sample cups contained hundreds of the same winged, ant-like insects I had been seeing under the logs.
As it turns out, these insects are exactly what they look like - they are ants with wings. And they were appearing in the nests I was observing in preparation for something called a nuptial flight, one of the most important annual events on an ant colony's calendar.
Under normal circumstances, most of the eggs laid by a queen ant will eventually produce workers, the standard looking, wingless insect that we all think of when we hear the word "ant." At a certain time of the year particular to each species, however, a nest may switch gears and start producing a caste of winged ants known as alates or swarmers. Unlike workers (which are all female), alates can be either male or female, and their main purpose is the establishment of new colonies. On hot, humid days, alates from multiple colonies all leave their nests at once and gather in large swarms, where they mate. Finding a mate is the end of the road for the male alates and they die soon after; the females, however, will fly off to find good spot where they can start a nest of their own, lay eggs and, eventually, become the queen of a whole new colony.
Nuptial flights are, at least in my opinion, one of nature's great, epic events. They are especially impressive in the boreal forests of northern New England and Atlantic Canada, but they occur all over the place and are similar to mayfly and cicada emergences in that they are important, temporary feeding events for all manner of birds, bats, and predatory insects. And yet, I would wager that very few readers know the term "nuptial flight." This is probably at least in part because in many species, the swarms are localized and fairly low-key, but I suspect it also has something to do with the swarms of alates that sometimes appear unexpectedly in homes hosting large ant colonies. When this happens, people tend to immediately call the exterminator, as my parents did when my siblings and I found a bunch of alates emerging behind out couch. The result is that if these events are usually discussed at all, it is usually in the context of pest control, rather than miracle of nature.
I certainly cannot begrudge my parents or anybody else for calling an exterminator in these situations. I remember protesting the death of the ants at the time, but gave up pretty quickly - in truth, I was a bit uncomfortable with their presence myself. There are humane ways to prevent ants from getting into and settling down in your house in the first place and I think we should all do our best to try these things first. When it reaches the point where you might have to worry about a yearly mass emergence of swarmers, however, I think it is perfectly understandable to want to force out your uninvited roommates.
And yet, at least for a nature loving kid like me, there was still a sense of wonder somewhere beneath my heebie-jeebies, as I came back again and again to watch the ants while we waited for the exterminator to arrive. There is something decentering about events like this, something that shifts your perspective and forces you to acknowledge whole words that exist on unfamiliar scales. In Walden, Henry David Thoreau dives into this feeling with his play-by-play narration of a battle between two ant colonies, lending the conflicts and concerns of these tiny insects the significance of epic history. A few months after I read this essay for the first time, I walked into the photography lab at my college and found something very similar playing out across the room's wide, tile plains - though it was more like a massacre than a battle. As best I can tell, the alates of one colony had emerged into the room, triggering alarms in another colony which sent out warriors from their own nest to neutralize the intruders. The result was a floor covered in alates vibrating severed wings, spinning in circles as ants from the other colony gather around, darting in here and there to slash at them with sharpened mandibles. I crouched in a corner where the battle hadn't yet reached and watched for a good hour, essentially abandoning my job testing the lab safety showers and eyewashes for the remainder of my shift. I had to work twice as fast the next day to catch up, but it was well worth it - the battle is still one of the most amazing things I have witnessed in nature.
Of course, I eventually had to report back to my boss, and I told her about what I had seen - the next class of photography students would have anyways. As far as I know, she called an exterminator and, at the very least, I never saw any ants in that room again. Still, the event stuck with me, joining the alates behind the couch and now, the ants in the insect traps, as memorable reminders that there are dramas of this sort constantly playing out just below and just above the scales of everyday life, even when we can't see them. One of the joys of urban ecology is realizing that they are even happening in your own backyard. Over the last couple of years, my dad and I have been collecting logs from trees taken down in my parent's neighborhood and piling them in their yard for the use of mushrooms and insects. I hope that one day, I'll stroll by these logs, notice a swarm of alates, and use my phone for nothing, but taking pictures.
Sources:
Ellison, A. M., Gotelli, N. J., Farnsworth, E. J., & Alpert, G. D. (2012). A field guide to the ants of New England. Yale University Press.
Photo Credits:
(1) "Winged Ants about to fly - TROML - 1159" - by Clint Budd (CC BY 2.0)
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