using a cannon to shoot a mosquito; excessive effort for a trivial task

Even a tiny bit is better than nothing at all; literally "even a mosquito, though tiny, is still meat".

The red bump or swelling on the skin left after a mosquito has bitten someone

(Taiwan, jocular) a public building that lies idle or is abandoned after construction, jokingly referred to as a place built only for housing mosquitoes.

spiral-shaped incense used for repelling or killing mosquitoes