Each year, seemingly out of nowhere, many of us witness a peculiar phenomenon: the sudden appearance of swarms of large, winged ants. One moment, your garden or local park is ant-free, and the next, it seems to be teeming with these flying insects. You might find yourself dodging them as they fill the air, wondering what has triggered this mass emergence.
So, what exactly causes this synchronized aerial display? Is there truly a ‘flying ant day’? Let’s delve into the fascinating world of these winged creatures to understand when and why flying ants take to the skies in such numbers.
Decoding Flying Ants: What Are They?
These flying ants are scientifically known as alates. In the UK, especially in urban environments, the winged insects you encounter are almost invariably the sexually mature queens and males of the black garden ant, Lasius niger. Distinguishing between them is quite straightforward: the larger ants are the queens, capable of reaching lengths of up to 15mm.
When Does Flying Ant Season Begin?
This yearly swarming event typically happens during July and August, aligning with periods of hot and humid weather. The exact timing of flying ant appearances can vary across the country, as local weather conditions play a crucial role in synchronizing their swarming activity.
Interestingly, flying ants tend to emerge earlier in urban areas compared to rural settings. This is likely due to the urban heat island effect, where temperatures in cities are generally warmer than in surrounding countryside.
The disruption caused by flying ants is even notorious enough to sometimes affect major sporting events like Wimbledon. In some years, these insects have plagued tennis players during matches, causing significant interruptions that even make headlines. However, it’s important to note that flying ant swarms can appear anytime between June and early September.
Contrary to the popular belief of a single ‘flying ant day’, a comprehensive citizen science project by the Royal Society of Biology revealed that it’s more accurately a ‘flying ant season’. Winged ants emerge over several weeks, often with multiple peaks in activity, each lasting just a few days. The specific swarming pattern changes from year to year, influenced by weather patterns.
Research indicates that swarming is primarily triggered by weather conditions. Ants are more likely to fly on days that are warm, not windy, and when conditions have improved compared to the preceding day. Anecdotal evidence also suggests that flying ant days often follow periods of summer rain.
Unearthing Their Origins: Where Do Flying Ants Come From?
Before their dramatic swarming display, flying ants live ordinary lives within established colonies in nests. Black garden ants prefer to nest in dry soil, commonly found in locations like flower beds, lawns, and under paving slabs or stones, with patios being a particularly favored spot. They thrive in almost any dry, open area warmed by the sun, including gardens, pavements, brownfield sites, heathland, grassland, and coastal regions.
In the weeks leading up to the swarming event, you might notice mounds of soil appearing above their nests, a subtle sign of the activity within.
Ant colonies operate on a caste system, with each individual having specific roles. The queen’s primary function is to lay eggs, while female workers care for the queen, eggs, and larvae. Workers also undertake tasks such as gathering food, expanding the nest, and ensuring the smooth functioning of the colony. While most eggs develop into workers, when the colony reaches maturity, the queen begins producing virgin queens and males.
When these winged males (drones) and virgin queens (princesses) emerge from the nest, they disperse widely. This scattering strategy is crucial for maximizing the chances of mating between ants from different colonies and minimizing inbreeding.
The Purpose of Flight: Why Do Ants Grow Wings?
Ant colonies have limited space for expansion. Eventually, a new queen must venture out to establish her own colony. To achieve this, she needs to mate with a male from a different colony and find a suitable location to start building a new nest. Growing wings and taking flight is the evolutionary solution that enables her to fulfill this essential task.
Therefore, each year, alates emerge from nests and embark on their nuptial flight. Their focus isn’t on humans or picnics; they are solely driven by the instinct to find a mate and reproduce. The sight of large winged females and smaller winged males flying in tandem is a common occurrence during this nuptial flight.
Swarming Behavior: Why the Sudden Mass Appearance?
Why do flying ants appear in such massive numbers, seemingly all at once? One primary reason is predator protection. There is genuine safety in numbers. By swarming, they overwhelm predators, ensuring that a significant proportion of the alates survive to mate.
Another critical reason for swarming is to maximize reproductive success. With a large concentration of their species in the air simultaneously, the ants don’t have to search far to find a mate. This mass emergence significantly increases the likelihood of successful mating encounters. During this brief, once-in-a-lifetime mating period, a queen typically mates with multiple males, ensuring genetic diversity for her future colony.
Life After the Nuptial Flight
Once mating is complete, the males’ role is finished. The mated queens quickly chew off their own wings and begin the crucial task of finding a suitable site to nest and establish a new colony. This explains why you often see larger, wingless ants walking around after a ‘flying ant day’, and you might even spot discarded wings scattered on pavements.
The ants observed throughout the rest of the year are the female workers, dedicated to foraging for food and maintaining the colony. After finding a suitable nesting location, the queen digs an underground chamber and lays her first batch of eggs, which she nurtures to adulthood. Remarkably, she will not eat for weeks, sustaining herself until her first generation of daughter workers are ready to forage and provide for her.
The sperm she received during the nuptial flight will last her entire life, enabling her to lay fertilized eggs for years to come. Queens of Lasius niger are exceptionally long-lived, often reproducing until their colonies reach thousands of individuals, with large nests potentially housing over 20,000 workers.
Lifespan of Flying Ants
Male flying ants have a short lifespan. They perform no tasks within the nest and are produced by the colony solely for the flying ant season. Developing from unfertilized eggs, their only purpose is to mate with new queens. After the nuptial flight, male ants typically survive for only another day or two, resulting in a total lifespan of just over a week.
In contrast, Lasius niger queens are remarkably long-lived, generally living for up to 15 years, with some recorded to reach 28 years in captivity. However, the winged or flying phase is a very small portion of their long lives, occurring only when they are young queens ready to establish their own colonies.
The Unexpected Benefits of Flying Ants
While flying ants might be considered a nuisance by some, their activities are actually beneficial to the ecosystem. Their tunneling contributes significantly to improving soil quality through aeration and nutrient distribution.
Furthermore, swarming events provide a crucial food source for numerous bird species. Swifts and gulls are frequently observed feeding frenziedly on swarming ants.
Black garden ants and the related cornfield ant (Lasius alienus) play a particularly important role in the survival of the silver-studded blue butterfly (Plebejus argus) in heathland habitats. Populations of this butterfly, known for its beauty, have declined across much of its range.
The ants and the butterfly have developed a mutually beneficial relationship. The ants protect the butterfly caterpillars from predators, and in return, they feed on sugary secretions produced by the caterpillars.
Ant Diversity in the UK
Ants, along with bees and wasps, belong to the insect order Hymenoptera, characterized by their three distinct body segments. The UK is home to approximately 60 ant species, all living in complex, social colonies.
Do Other Ant Species Fly?
While the black garden ant is the most commonly observed flying ant, the nuptial flight is a critical reproductive stage for most, though not all, ant species. Red ants (Myrmica rubra) are another common ant species in Britain that also develop wings and swarm. However, surveys conducted by the Royal Society of Biology indicated that nearly 90% of winged ants observed were black garden ants (Lasius niger), also known as the common black ant.
The type of flying ant you encounter will depend on your location. For instance, wood ants might be more prevalent in woodland areas. Crucially, all ant species require favorable weather conditions for flight, specifically avoiding rain and wind. The temperature and humidity thresholds that trigger swarming and flight differ for each species, leading to variations in the timing of their nuptial flights throughout the flying ant season.
In conclusion, the sudden appearance of flying ants is a natural and fascinating phenomenon, driven by the reproductive needs of ant colonies and synchronized by environmental cues. While they may be briefly bothersome, their ecological roles are undeniably beneficial, contributing to soil health and supporting biodiversity.
