Flying ants

[kujawski]

Why do all flying ants emerge from their nest at about the same time?

[tazz]

they all seem to come out when its been hot, so its something to do with heat

[lugus]

They all emerge together in order to escape predators. Sounds daft but any predator in the vacinity will soon become overwhelmed by the amount of food and the majority will escape.
Any one nest will actually do this twice. Once for the females (the big fat ones) and once for the males (the little weedy ones) this cuts down on the chances of inbreeding.