These insects are basically just weather people

Published: October 7, 2019

crickets-on-a-leaf Photo by artpritsadee/Shutterstock

The insects at the lake do more than just provide a symphonic backdrop to our warm-weather days and nights. Some of them are giving us a surprisingly accurate weather report.

Consider crickets, for instance. According to The Farmer’s Almanac, a scientist named Amos Dolbear created a formula based on a correlation between the ambient temperature and the rate of crickets’ chirping. It became known as Dolbear’s Law and consists of counting the number of cricket chirps in 14 seconds and then adding 40 to get the temperature in Fahrenheit. To get it in Celsius, says the almanac, count the number of chirps in 25 seconds, divide by 3, then add 4.

Crickets are cold-blooded, which means they take on the temperature of their surroundings. The warmer it gets, the more limber they are, similar to humans, and the more quickly crickets can create the chemical muscle reactions that generate the chirping sound.

Crickets make their chirping sound — whether to attract a mate, ward off a competitor, or sound the alarm — by rubbing the edges of their wings together, akin to running your finger along the teeth of a plastic comb.

If you’re hearing the sometimes deafening sound of cicadas, you can be sure that the ground has thawed to a temperature of just shy of 18°C. Cicada nymphs remain in the soil, feeding, until the temperature reaches exactly 17.7°C (64°F), when they burrow to the surface, climb the nearest vertical object (including a human), and begin their…let’s call it song.

Plenty of other insects are good at predicting rain, according to researchers at Western University in London, Ontario. Specifically, the cucurbit beetle, the true armyworm moth, and the potato aphid indicated that they sensed a change in atmospheric pressure preceding rain. Their indicators, though, were somewhat … private. For instance, male beetles were less responsive to female pheromones and though they would still mate if they were close to a female beetle, they eschewed foreplay and went straight to copulation, “as if they were trying to get it over with quickly, before a deadly storm arrived,” according to a paper published in the academic journal Nature.

Moths and aphids responded similarly. If rain threatened, the females of both species reduced their “calling” behaviour, in part, researchers suspect, because their mating behaviour — perched on the edges of leaves — made them more vulnerable in windy, rainy weather.

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