Myrmica in September: the last UK flights

Every September a few winged ants turn up on washing lines and windowsills and get reported, with mild indignation, as flying ant day running late. It isn't. July's headliner, the black garden ant, has finished. What's flying now is mostly Myrmica, the red ants, and they are a different animal in almost every way that matters: smaller, redder, later, lower, and armed.

You already know these ants, even if you've never named them. They're the reason kneeling on certain patches of lawn stings.

Let's do the reassurance properly, since these are the red ones. Myrmica carries a real sting, which the black garden ant doesn't, and a disturbed nest will use it. On human skin it lands somewhere around a nettle: sharp for a second, gone within the hour, no mark to show for it.

The flight itself asks nothing of you. Winged queens and males are leaving home, they don't defend, and by evening the whole event is over. The only practical advice is the same as July's: if they're drifting in through an open window, close it for an hour and let them get on with it. We covered the indoor scenario in flying ants in your house, and every word of it applies in September.

There's a real physical reason the season stretches this far, and it was worked out decades ago by two Dutch researchers who recorded the weather at the exact moments queens took off. Boomsma & Leusink (1981) found the temperature ranges of the big July flyer and the red ants overlap almost completely. What separated them was light. Black garden ant flights needed strong sun; Myrmica flights ran on a fraction of it.

The explanation is baggage. A black garden ant queen is a heavy insect that suns herself up to operating temperature before takeoff. A Myrmica queen weighs about 4 mg, a sixth of that, and can get airborne without the solar assist. So while July's swarms wait for hot, bright afternoons, September's red ants will use a warm, grey, entirely ordinary one. British recording has their flights from July right through September, some species leaning to the late end.

Less fussy also means less synchronised, which is why nobody's coined a Red Ant Day. Instead of one roaring afternoon you get small local bursts: a few dozen ants off one nest entrance, at almost any hour, on dates scattered across weeks.

Lower your eyes. July's spectacle was columns over rooftops; September's is a shimmer at grass height, usually within a metre or two (a few feet) of the nest. Rough lawns, grass tussocks, path edges and old flowerbeds are the launch pads. If you want the full cast of Britain's late season, thief ants, parasitic queens, October's Stenamma, the keeper-grade tour is in the second wave.

And if you'd like to know whether this particular grey afternoon is one of theirs: that's what Dealate does, scoring each species still in season at your location, hour by hour, from live weather. A reason to look up, not a guarantee.