expression, godan verb (-gu)
be itching to do something; have an urge to do something
Idiomatic expression describing a restless, instinctive urge to act, often despite knowing better. The 'bug' (虫) metaphor suggests an inner impulse that is hard to suppress.
危ないとわかっていても、虫が騒いでつい冒険してしまう。
Even though I know it's dangerous, I get an itch to do it and end up taking the risk.
彼は虫が騒いで、夜中にこっそり家を抜け出した。
He felt an irresistible urge and sneaked out of the house in the middle of the night.