AS YOU will have noticed from your Irish Times on Saturday, and maybe even from personal experience, swarms of flying ants have been much in evidence of late. As has been pointed out, there is nothing very unusual in this it happens every year in late summer, the trigger being a spell of quiet settled weather.
Ants have the reputation of being shrewd observers, and even predictors, of the weather. As rain approaches, it is said, they can be seen running to and fro carrying their eggs to a more protected spot. One of the earliest to note this precautionary ritual was the Roman poet Virgil, whose comments on the subject were translated into English by John Dryden in the 17th century.
For ere the rising winds begin to roar,
The careful ant her secret cell forsakes
The ants' behaviour may well be prompted by subtle changes in the humidity undetectable to you and me, and has given rise to the superstition common in many cultures that stepping on ants will bring the rain if the ants are there to be stepped upon, it may well be that the rain is on the way in any case.
It is often said, however, that it is not to what the ants are doing, but to ho's they do it, that we should look for weather clues. We are told, for example, that when they expect bad weather, they travel in straight, regimented lines, whereas if good weather is on the way, ants going about their normal business spread out and cover wide areas. Moreover, they allegedly run faster in warm weather than they do when it is cool, to the extent that an approximation to the air temperature may be obtained by timing the speed of movement of the busy insects.
It may be in this thermometric skill that we can find the answer to the recent swarms. Continuation of the species depends on the successful mating "on the wing" of the winged males and queens in late summer, an exercise which, understandably, is most effectively accomplished in dry, calm conditions. The eager potential procreators are carefully pampered in their nests by the wingless workers, often for several weeks, until conditions are exactly right. Meanwhile, the workers monitor the temperature and humidity outside, waiting for the perfect mating weather to arrive.
When a period of stable anticyclonic weather is at hand, the worker ants release a chemical into the air that stimulates the males and queens to emerge simultaneously form hundreds of nests over many square miles. The result is a swarm of the kind we have seen recently, during which many an antly nuptial is consummated.