An egg timer with a bell ding at the end.
I needed a good indoor fish tank for an office scene I was working on, and made one out of ...
Buzz of a Neon light, steady
Switching on old neon lamp, blinking and buzzing rec by Zoom H2
insect buzzing around the mic, bird calls in background. BP4025 stereo mic into Shure FP24 preamp, Olympus LS10 recorder
A lot of flies on a warm day near something smelly...
Hundreds of flies under the verandah, keeping cool on a really hot day.