Fig.: to be extremely restless, jumpy, anxious

I don't know how you keep up with that child of yours: he must have ants in his pants because he can't keep still for a moment

Non so come fai a tener dietro al tuo bambino: ha proprio l'argento vivo addosso e non sta fermo un attimo

Calm down! What's the matter with you? Do you have ants in your pants?

Vuoi calmarti?!? Che cosa ti ha preso? Ti ha morso la tarantola?

The babysitter will have her hands full with those little twins. They are two live wires and will stress out anyone

La baby sitter avrà il suo bel daffare con quei due gemellini. Hanno l'argento vivo addosso e stresserebbero chiunque

This rhyming idiom comes from the 17th-century expression “a breeze (gadfly) in one's breech(es).” The cliché also gave rise to the slangy adjective “antsy”