Flying ants nesting between patio paving slabs

I walked down the top steps from the house towards the garden and suddenly saw hundreds of flying ants emerging from a crack between the steps. A pile of grains of what looked like sand was raised up beside the crack and ordinary ants were milling about the winged ants.

An hour or so later I went to refill the sunflower feeder on the patio which is down another flight of steep steps. As I walked over the large 4' by 2' sandstone paving slabs I saw the flying ants were now moving about, in and out of these much wider cracks, with much smaller wingless ants supporting them. I assume these were like worker 'bees' supporting queen bees in their nests or hives.

I went to fetch my camera as I knew these moments are very brief with flying ants appearing for just a few hours at a time. I don’t know what their appearance represents in their life cycles so I must try and find out.

I became interested in them back in 1982 when I was staying for six weeks on a beach on an island in Thailand. I’d gone to have a long holiday before  travelling around parts of south-east asia, at the beginning of a fifteen month journey.

That day I was swimming in the warm sea as dusk approached with the delightful thought of having a few beers and a meal in the palm hut of the owners of collection of palm leaf huts. This small and simple beach side encampment was in a plantation of coconut palms, with a small restaurant at the far end of the beach, also made of palm leaves and bamboo with a few bits of hard wood as flooring.

As I swam that day I noticed a small cloud near the beach edge and then some insects landed on my head in the water. The cloud became much larger and I saw the owners of the bungalows rushing around collecting old dried palm leaves from wherever they could find them. They piled them up in a big heap and then set fire to pile. Being tinder dry the fire rapidly became a small inferno with bright flames reaching up towards the sky.

It was only afterwards when I got out of the water that I learnt from them that these flying ants were large, they bit and were dangerous to humans. The locals knew that the light from the flames would attract the ants in the near darkness, and they would be drawn into the flames. It worked and within a few minutes the mass of ants had disappeared, and the normal calm of early evening returned. The few of us there who were tourists could then relax once again, our normal very lazy life style could return thanks to the quick wittedness of our hosts. Only a few bites remained on me to prove the short event had actually happened.

This article gives a reasonably good description of what happens and why.