Camping Out (known as Camping Troubles in early releases outside the United States) is a Mickey Mouse short that was released on February 17, 1934.
Mickey, Minnie, Horace, and Clarabelle are sitting around their campsite when a mosquito spoils their fun. And then he gets hundreds of his friends and they really cause trouble. Horace squirts some with molasses, which helps a bit. Everyone retreats to the tent, where they still get stung but can fight back a bit, eventually trapping all the mosquitoes in a pair of bloomers and sending them on their way.