Animal of the Week -- July 16, 2007

Well, it's that time of year again, when an afternoon outside becomes a constant battle against foe whose endless onslaught is like nothing seen outside a Lord of the Rings battle scene. No sooner have you shaken one from your hair than another lands in your cleavage, and when you've picked that out, you find three have landed in your drink/on your ice cream/in your mouth. And what is this haphazard winged plague of summer? Lasius niger (black garden ants), that's what.

You may wonder what triggers this aerial onslaught, when generally ants aren't that noted for their flying, and are most annoying for dying in your sugarbowl. Our insect tormentors are either queens, the most prominent fat ones, or males, the little ones that you see but don't really mind about because they're much less custardy. This is the only time that the ants will fly, hence their lack of proficiency.

On this, their nuptial flight, the males and females will mate, and with the juices of the male safely apportioned, he will die, the queen will lose her wings and tunnel underground and begin to lay eggs. The fertilised eggs hatch and the larvae become female workers. Throughout the rest of the year the colony swells as more and more workers hatch out of the never ending supply of eggs from the distended and immobile queen. The colony spreads further and further looking for food, getting into your cupboards dying in the threads of your jam-jar lids, wandering off with the contents of picnic baskets, and getting in your pants. What else do ants do?

As summer approaches, the workers decide it's time for the success of the colony to be spread even further, and they select some eggs (still fertilised by the product of the nuptial flight) to raise as dispersing queens, and the queen lays some unfertilised eggs that will become males. Triggered by cues of daylength, temperature, and humidity with astounding and fearsome synchronicity colonies all over an area crack open and the winged horde takes flight. The mass eruption means that queens of one colony might mate with males of another rather than with their own brothers.

The flying menace some years reaches such proportions that they clog air-conditioning and trigger mass congregations of sea gulls and swallows, which come to feast on the glut. Humans deal with the event by flapping, moaning, squashing and beating them from the sky with badminton racquets. I say let them be, they'll be gone as soon and as suddenly as they came.

One downside of black ant for the gardeners among you is that they farm aphids, protecting them from predators while harvesting a sticky secretion called honeydew (the nasty smut that gathers on a car parked under a lime tree). In the picture, a black ant is carrying an aphid in its jaws.