The ant flight timetable: who flies at dawn, who flies at nine at night

"Flying ant day" gets all the attention, but there's a quieter assumption sitting underneath it, which is that when ants do fly, they fly in the middle of a hot afternoon.

Some do. A lot don't. Nuptial flights are scattered right across the twenty-four hours, and several of the most interesting ones happen when there is nobody outside to see them.

If you only ever look at lunchtime, there are whole genera you will never once catch in the air.

The Texas leafcutter, Atta texana, flies in the dark, in a narrow slot somewhere around three to four in the morning. It's the outlier of outliers, and it's a large part of why leafcutter flights get missed so completely. The whole thing is finished before sunrise.

Veromessor doesn't wait around either. Its flights are cued by day length rather than heat, and they peak inside the first hour of daylight, which makes it one of the more predictable genera and one of the least convenient. Cyphomyrmex rimosus goes earlier still, launching at the first faint grey of dawn, and only after heavy rain.

Both of those mean setting an alarm.

Dolichoderus mariae flies in a tight window from about seven to half past eight, again after rain (Laskis and Tschinkel documented this one properly in 2009). Oecophylla smaragdina, the Asian weaver ant, peaks mid-morning.

Worth flagging, because it's a nice warning about how far you can push a genus-level rule: the African weaver ant, Oecophylla longinoda, flies at dusk. Same genus, opposite end of the day. Genus is a useful unit right up to the point where it suddenly isn't.

Forelius pruinosus has been nicknamed the High Noon Ant, which does most of the explaining for me. It flies in the hottest, brightest part of the day, when a good deal of everything else has gone to ground.

That's about it for midday, which is the point.

Pogonomyrmex, the harvester ants, fly a few hours after solar noon, roughly half three to five, and usually in the wake of a monsoon storm. In the American Southwest this is the great set-piece flight of the year and it's worth planning a week around.

Aphaenogaster starts about forty-five minutes before sunset. It's a short window and it closes fast, and it lands at exactly the time of day most people have stopped paying attention.

Camponotus, the carpenter ants, are the reason it's worth walking past a lit porch in June. They fly in the evening and they come to light, and Camponotus castaneus concentrates around nine at night. Technomyrmex albipes does much the same thing at dusk.

Stenamma is properly nocturnal and flies as late as October, which makes it the last flight of the year across a lot of the northern range. If you've written the season off in September you have written it off too early.

And then there's Tetramorium forte, which refuses to choose. It has two peaks, one around six in the morning and another around eight in the evening, and it skips the middle of the day altogether.

Some of it is hazard. A queen has to survive her own flight, and what's trying to kill her changes by the hour: birds in daylight, heat and desiccation at midday, a colder body and different predators at night. Different species have taken different bets on which risk to run.

The rest of it is about staying separate. A nuptial flight only works if a colony's queens and males meet queens and males from other colonies of the same species, rather than a cloud of something unrelated. Flying at an hour your neighbours don't fly is a cheap and reliable way to arrange that. Where two related species share a season and a habitat, they very often split the clock instead.

The day is only half the question, and it's the half everybody focuses on.

Getting the date right and then standing outside at the wrong hour will show you precisely nothing, and it's the most common way a well-timed evening ends in an empty notebook. A genus that flies forty-five minutes before sunset is giving you a window shorter than most people's commute.

That's the reason Dealate scores an hour-by-hour window rather than just a day, and scores it separately per species. The answer for Camponotus and the answer for Veromessor, on the same lawn on the same afternoon, are twelve hours apart.

A reason to look up, at the right time. Still not a guarantee.

The timings above come from the primary literature, including Laskis & Tschinkel (2009) on Dolichoderus mariae and the flight-timing records collected in AntWiki's nuptial flight compilations. The reasoning behind the model, and the papers it leans on, are set out on the methodology page.