The first warm rain falls, the windows mist up and, almost on cue, hundreds of winged insects appear around outside lights.

By morning, the swarm has disappeared, leaving scattered wings across patios, windowsills and floors.

Joburg residents often call them “flying ants” or rysmiere. Although genuine flying ants also exist, many of the insects seen after Highveld summer rain are reproductive termites known as alates.

Rain provides the starting signal.

Rain didn't create the termites, nor did they suddenly appear. They developed inside an established colony and waited for suitable conditions before emerging.

Research on the southern African fungus-growing termite Macrotermes natalensis found that rainfall was the main trigger for its early-summer dispersal flights. Temperature, wind and light levels also influenced when the termites left their nests.

Warm, humid conditions give the poorly flying insects a better opportunity to disperse without drying out. Moist ground may also make it easier for successful pairs to begin establishing a protected nest.

The insects often emerge together in enormous numbers because most will not survive. Birds, reptiles and other animals quickly take advantage of the sudden feast. SANBI records birds, mammals and reptiles among the predators that eat harvester termites. 

This is the colony’s next generation.

A termite colony contains different groups with specialised jobs, including workers, soldiers and reproductive termites.

The alates are potential future kings and queens. They temporarily possess wings so that they can leave their original colony and disperse.

After a relatively short flight, they land and twist their bodies until their wings break away. A male and female that successfully pair may then attempt to establish a new colony together. 

That explains the neat piles of loose wings left behind after a swarm. They don't necessarily show that insects have been eaten or killed; termites are designed to discard them.

Why do they gather around lights?

Many termite alates are attracted to light during their dispersal flight. In an urban neighbourhood, a bright patio light, window or security light can pull large numbers away from their normal route.

Research shows attraction can vary with light intensity and wavelength. Once the termites land and lose their wings, however, their behaviour changes and they begin seeking shelter instead. 

Switching off unnecessary outside lights and closing curtains during a swarm may reduce the number gathering around a home. However, it will not remove an established termite colony.

Ant or termite? Look at the body.

Colour alone is not a reliable guide because both groups can range from light brown to almost black.

Instead, look at three physical differences:

• Waist: A termite has a comparatively broad, straight body. An ant has a clearly pinched waist.
• Antennae: Termite antennae are straight or gently curved. Ant antennae have a noticeable elbow.
• Wings: A termite’s four wings are approximately equal in length. An ant’s front wings are longer than its rear wings. 

Here is another surprising fact: despite commonly being called “white ants”, termites are not ants. Modern classification places termites and cockroaches together in the order Blattodea. They are more closely related to cockroaches than to true ants.

Does a swarm mean your home is infested?

Not necessarily.

A swarm around an outside light may have flown in from surrounding soil, open land or a colony elsewhere in the neighbourhood. Seeing termites outdoors therefore doesn't prove they are damaging the building.

Location matters. Termites emerging from a wall, skirting board, wooden fitting or another point inside a closed building deserve closer attention. Repeated indoor swarms, mud-like shelter tubes, hollow or damaged timber and recurring piles of wings may justify an inspection by a properly qualified pest-control professional.

Careful identification matters because not every termite species attacks buildings, and the right response depends on the species and where the colony is located. Seeing an outdoor swarm alone is not a reason to assume that a home is infested or to apply chemicals indiscriminately. 

Nature’s overlooked recycling team

Termites have a terrible reputation because certain species can damage timber. In natural environments, however, they perform essential work.

They break down dead grass, wood and other plant material, returning nutrients to the soil. Their underground movement contributes to soil formation, aeration and water infiltration, which is why scientists describe them as ecosystem engineers. 

A University of Pretoria study in a South African savanna found that termites were responsible for a substantial share of the decomposition of dry wood and also contributed to breaking down grass and dung. 

They are also an important seasonal food source for birds and other animals. The chaotic swarm around a light is therefore part of a much larger ecological event: colonies dispersing, predators feeding and nutrients continuing to move through the environment.

The Bottom Line

Those post-rain “flying ants” are often termite alates on a brief and dangerous mission to begin new colonies.

Most will never succeed. But before reaching for the insect spray, take a closer look: the swarm outside may be one of Joburg’s most remarkable, and misunderstood, summer spectacles.