It’s supposed to be automatic, but actually you have to push this button.

“As I travelled south through Europe everything got bigger. This applied to nice things like fruit-the nectarines and tomatoes were about six times as large in Greece as they were in Britain for example. But the principle also applied to unpleasant things, like spiders, and worms, and all other nameless and horrifying insects and arachnids of Greece.”
— Margaret Eleanor Leigh