Book club: Some notes on flying ant day, and other such swarms

An extract from Lev Parikian's Taking Flight: The Evolutionary Story of Life on the Wing.

Hello everyone. Earlier this year I used this newsletter to publish an extract from my friend James Vincent’s book Beyond Measure: The Hidden History of Measurement. That seemed to go down well, and sell a few copies of a fantastic book, so I was planning to make it a regular thing, and had just agreed to run this chunk of Daniel Knowles’ Carmageddon: How Cars Make Life Worse and What to Do About It when my life imploded and I forgot all about it. 

It’s still a good idea, though; so this is the first of a new, monthly-ish thread I’m calling (highly original, this) “Book club”. This one's from Lev Parikian's Taking Flight: The Evolutionary Story of Life on the Wing, which was just shortlisted for the Royal Society Book Prize, and concerns a mystery for the ages: what, when and why, exactly, is flying ant day? If you enjoy it (and you should, it's brilliant) then why not buy the book? 

I'm off to Labour conference, the happiest place on Earth. I'll be back with something written by me on Wednesday. The next voice you hear will be Lev's.

The concept of “flying ant day” is familiar to many people, especially tennis fans. It disrupts proceedings at Wimbledon most years, much to the amusement of the (frankly quite easily amused) Centre Court crowd. But “flying ant day” is a misnomer, because it’s not just a single day but a season, usually lasting from June to August.

They like it warm. They like it still. There’s some evidence they like it when it’s just rained. Whatever the trigger, for most people “flying ant day” is a mild and temporary nuisance. For others it’s a neat excuse to get on their local Facebook page and ask, “What is it with these effin’ ants??!!” And for a few enlightened souls it’s an opportunity to observe ant behaviour at close hand. Though, admittedly, if you’re caught in the middle of a swarm, the phenomenon can be overwhelming.

You might get an early sign that the ants have taken to the air by observing the behaviour of gulls. They like an ant, do gulls, and when the air is filled with them, the birds perform mid-air gyrations worthy of an experimental dance troupe in their efforts to gorge on the sudden appearance of an all-you-can-eat buffet.

The motivation for this burst of aerial activity is dispersal – a straightforward way to diversify the gene pool. When the time is right, the queen switches – instead of laying female worker eggs, she lays male drones and virgin queens. Once hatched, these ants grow wings and take to the air in huge numbers, the idea being not only the usual “safety in numbers” strategy but also to give them a better chance of meeting a mate from another colony. The queens mate with as many males as they can in their brief time in the air. For the males, this is their only purpose in life, and once they’ve flown and mated, they die. For her part, and showing admirable pragmatism, the queen will chew off her own wings and begin the search for a suitable site to set up a new colony.

Ant and bee swarms, despite our paranoid fears, are mainly benevolent. We might be relieved that they haven’t taken inspiration from locusts. Unrelated to the hymenopterans except in the loosest “also an insect” sense, they are nevertheless worth brief examination because of their simply extraordinary swarming abilities. Usually solitary, they undergo a genetic shift when conditions align, and become highly gregarious animals with an urge to breed en masse and swarm. And when they swarm, they properly swarm. Stories of millions of locusts blocking out the sun are as old as we are. They were, after all, one of the ten plagues visited on Egypt by God:

“God told Moses to stretch out his hand over the land of Egypt to bring a plague of locusts. The locusts covered the face of the land and swallowed up every crop and all the fruits of the trees. Afterwards there was nothing green in the trees, and all the crops in the fields had been destroyed.”

This isn’t, to judge by multiple accounts over many centuries, hyperbole. And these nomadic swarms still happen from time to time, presenting as much of a threat to the livelihood of farmers as they ever did, as evidenced by a series of massive swarms in East Africa in 2020. After a period of drought was followed by abundant rainfall, vegetation grew rapidly in the wet, sandy soil that locusts prefer, and the conditions were perfect for a breeding surge. One swarm in Kenya was reported to cover an area of 2,400 square kilometres. They can travel up to 160km a day with the help of prevailing winds. Swarm, move, eat. And they do eat – approximately their own body weight on a daily basis. Trillions of insects descending on farmland can take out entire crops with devastating speed.

A swarm can be a rather more low-key gathering. Spiralling columns of nameless tiddlers in the garden of an early summer evening constitute a swarm of sorts. And while some insects swarm for specific reasons – breeding and feeding, as so often, come top of the list – sometimes the formation of a swarm is simply the result of a lot of insects of the same species being in the same place at the same time. There’s no particular purpose to these swarms – they just are.

It’ll come as a relief, after all this talk of nightmarish gatherings, to learn that wasps – the most reviled members of the Hymenoptera – are more unwilling swarmers. Which isn’t to say they don’t do it at all – just try attacking an active nest and see how you get on. But for social wasps, swarming is a defence against threat rather than a population dispersal strategy. The relative rarity of swarming in wasps, however, might be the best thing many people have to say about them, such is their lowly position in our estimation.

Plutarch suggested that wasps were degenerate bees, and this assessment prevails to this day. The general perception of wasps as useless and vindictive is deeply ingrained, largely based on the very few species we encounter on a regular basis – the yellowjackets and similar types that hang around our picnics and, so we think, sting us without the slightest provocation. Inconveniently for this anti-wasp narrative, the truth is (as so often) more nuanced than that, not least because there are so many species of wasp, the large majority living their lives away from the human gaze. It’s true that some of them lead what human sensibilities consider unsavoury existences. The many species of parasitoid wasps have habits that are not for the faint of heart, involving – as the word “parasitoid” implies – mostly the infiltration of a host organism, leading to its eventual death. Placed next to this kind of behaviour, the perceived annoyingness of yellowjackets seems almost mild and eminently forgivable.

Almost.

Bees and wasps developed their sting not, as we would like to believe, as a form of unprovoked attack, but as a defence against predators, and, like it or not, that is exactly how they perceive us. We are, after all, the very large and often flailing monster stopping them from settling down on the picnic table and having a good old slurp of that blob of ketchup. Of course they’re going to feel threatened by us. The sting is a sort of last resort – they’ve tried flying around in fast and unpredictable patterns, and yet still we flail. If they’re lucky enough to get close to us without being splatted, the sting might just be the thing that sees us off. And when a stinging event takes place, they summon help.

Bee or wasp stings are, for most people, no more than painful inconveniences (although of course if you’re allergic to stings, it is of course more serious than that). There is, however, one crucial difference. When you’re stung by a female honey bee (the male drones don’t sting), the sting, equipped with strong barbs, remains embedded, while the bee is eviscerated. A wasp retains its sting and is able to attack again. But in both cases a pheromone is released to summon the hordes and attack the enemy (that’s you), and this is when a gathering of bees (not strictly speaking called a swarm in these circumstances) does pose a threat, because if you happen to be near a hive, this could be bad news. Honey bees aren’t the fastest in the air, but they can reach speeds of up to 25 or 30 km/h – plenty fast enough to outpace a human. In this case their flight path will be admirably direct. Bees summoned by an attack pheromone, unlike a swarming colony relocating to its new home, complete the journey without passing ‘Go’ or collecting £200. We might find a moment to admire their efficiency, had we the leisure to observe it.

Meanwhile, we console ourselves with the fact that this scenario – given that most people are stung by a bee or wasp no more than once every ten or fifteen years – is more worrying in theory than in practice.

Lev Parikian is a writer and conductor. His latest book, Taking Flight: The Evolutionary Story of Life on the Wing, is available here. It’s been shortlisted for the Royal Society Book Prize. This has surprised him so much that he can’t get out of the habit of telling people about it. He has a Substack called Six Things.