Right now, trillions of crickets are crawling out of the ground across much of the midwestern and eastern US. And this year is extra special, because two hatchlings burst out of the ground at once. The first brood was not seen for 13 years, the other for 17 years and the last time they emerged together Thomas Jefferson was president. Ian Sample talks to entomologist Dr Gene Kritsky to find out what’s going on, why periodic cicadas emerge in cycles of prime numbers and how they keep time underground
How to listen to podcasts: everything you need to know
