For millennia, human beings have looked to the behaviour of animals around them to determine the weather.
Discover our latest podcast
The change in behaviour of some insects and spiders have been of particular help to sailors and farmers of old in predicting what the weather would be. For instance, when spiders appear to be busy spinning webs in the middle of the day, that is taken as a sign that the weather would remain clear.
Other such observations include a correlation between how quickly crickets chirp and weather temperature.It was also believed that winter would be extremely cold if ant-hills are high in July.
Scientific explanation
Before you rush to dismiss these old methods of weather forecasting as mere superstitions, scientists have been looking into how some insects alter their behaviours in response to changes in atmospheric pressure.
For instance, a professor at at the Department of Animal Biology at the University of Illinois, Dr. Ken Paige, explained that insects and flies tend to bite before a storm because:
They are likely responding to falling barometric pressure preceding rainfall.
According to him, it is necessary for insects to predict changes in the atmosphere as being caught in a storm could be fatal for them.
Sex and the weather
Researchers have also found that some insects are likely to shy away from sex in response to a drop in atmospheric pressure which usually precedes rainfall.
A team of entomologists at the University of São Paulo in Brazil studied mating behaviour changes in the cucurbit beetle, the true army-worm moth, and the potato aphid under different air pressure conditions.
Under stable or rising air pressure conditions, all males displayed normal mating behaviour, showing that bad weather can reduce the sexual drive in some insects.
The lead researcher, Dr. José Bento explained their findings:
The results presented show that three very different insect species all modify aspects of their sexual behaviour in response to changing barometric pressure...However, there is a great deal of interspecific variability in their responses that can be related to differences in size, flight ability and the periodicity of mating.
