The annual insect spectacle you may have overlooked
Peterborough Examiner – September 12, 2025 – by Drew Monkman
On warm, muggy days in late summer, we are treated to a fascinating glimpse into the lives of ants. Although we rarely think of ants as winged creatures, they do grow wings during the mating phase of their life cycle. It is then that we witness swarms clustering on sidewalks, rocks, windowsills, or drifting overhead. Each September, our own Peterborough backyard hosts this spectacle as hundreds of winged ants often congregate around our birdbath.
Ants belong to the order Hymenoptera, which also includes bees and wasps. Like monarch butterflies, they undergo complete metamorphosis: egg, larva, pupa, and adult. Eggs hatch into blind, legless larvae—little white eating machines—fed constantly by workers until they pupate. Pupae resemble adults but with legs and antennae folded against their bodies. After a resting stage, the adult emerges, pale at first but soon darkening.
If you flip over a stone, you may glimpse workers rushing to carry eggs, larvae and pupae to safety. It’s a peek into the colony’s usually hidden nursery.
A society of specialists
Ant colonies are built on cooperation. Nearly all members are sterile female workers – usually smaller than queens and males – who care for the young, tend the queen, expand the nest, and forage. There is no leader—tasks shift constantly, guided by chemical signals called pheromones. A pheromone sets off a response in another individual of the same species. There are, for example, sex pheromones, alarm pheromones, and food trail pheromones.
Workers may live six years, while queens can survive more than a decade. Males, however, exist only to reproduce. They hatch from unfertilized eggs, develop wings, and die soon after mating.
Swarming
An ant colony can only expand so much. New queens need to strike out on their own, mate with males from another colony and find a new location to nest. Wings give them the means to fly off and begin anew.
This brings us to the most dramatic moment in an ant’s life cycle: the mating swarm, or “nuptial flight.” On warm, humid afternoons and often a few days after rain, thousands of winged males and females – known as alates – erupt from the ground, pushed out by the workers.
Females – virgin queens – release powerful pheromones, drawing in the smaller males. Mating often takes place on the wing. Each new queen stores enough sperm to fertilize eggs for the rest of her life. Once mated, she bites off her wings, reabsorbs nutrients from her wing muscles and hides away to raise her first brood alone. Her daughters then assume colony duties, and the cycle begins anew.
An especially interesting behaviour of some mating swarms is known as “hill topping”. In an effort to more easily find a mate, ants congregate around prominent points of a landscape such as a birdbath, a tree, or a chimney. Although they occasionally fall down chimneys into houses, there is no risk of an infestation.
Swarming behavior is usually synchronized with other ant colonies of the same species so that it occurs on the same day and over large areas. The swarming of multiple ant colonies promotes interbreeding which increases genetic diversity and adaptability.
Stop and observe
If you stop and look carefully at the ground where winged ants are clustering, you might see the tiny worker ants actively helping the winged queens and males emerge from the underground nest. The workers dig or push at the soil, clear tunnels and nudge or pull their winged kindred toward the surface. It’s a fascinating glimpse of teamwork in a tiny society.
Swarming ants are a bonanza for predators. Dragonflies, swifts and swallows snatch them effortlessly out of mid-air. Even ring-billed gulls, surprisingly nimble as aerial foragers, take advantage of this source of easy food. At a cottage one September, my wife and I watched as dozens of darner dragonflies feasted on flying ants that were swarming over the dock. One even landed on my arm, nonchalantly chewing its prey.
Familiar local species
Even in a quiet backyard, ants are busy at work, performing vital roles we often overlook. One of the most familiar is the carpenter ant (Camponotus species). These large ants don’t eat wood—they only tunnel through it to build nests—but they are expert foragers, collecting sugary foodslike nectar and honeydew, as well as protein-rich insectsto feed their larvae. Carpenter ants will also tend aphids, protecting these tiny sap-suckers in exchange for sweet honeydew, a fascinating example of insect mutualism in action. They usually swarm in late spring.
Another common group is field ants (Formica species), the classic mound builders. They are typically black or black and red. Formicine ants have a distinctive node (body part) between the thorax and the abdomen. They also smell of formic acid which serves purposes ranging from communication to defense. These ants are beneficial in the garden, aerating soil, recycling nutrients, and keeping pest insects in check. Their mounds are more of a curiosity than a threat.
Ants also disperse seeds. Many spring wildflowers, such as trilliums and violets, have nutrient-rich pouches attached to their seeds. Ants carry them underground, eat the pouch, and leave the seed in a moist, fertile setting. This ancient partnership has shaped the spread of countless forest plants.
Climate change and fire ants
Fire ants, infamous for their painful sting, aggressive swarms and damage to ecosystems, are not yet established in Ontario. Native to South America, they’ve spread through the southern U.S. and beyond, but cold winters here have so far kept them at bay. Climate change, however, may tip the balance. Warmer winters and accidental transport in soil, plants, or freight could allow them to survive, especially in frost-protected urban areas. Scientists warn that with 2 to 4C of warming, southern Ontario may become suitable habitat. The prospect of fire ants moving north is a reminder of how warming climates invite unwelcome guests.
From improving garden ecosystems and dispersing seeds to their role as prey and predator, ants are key players in the natural world. If you notice a mating swarm, take a few moments to watch and to think about the intricate web of connections that this amazing phenomenon so abundantly displays.
