This song is written to a mosquito who had landed on Cheryl's arm on March 27, 1998, which is very early to see a mosquito in Mass. It was surely this mosquito's first night out, so she didn't want to kill it. So she wrote a song about it instead.
During the intro to this song, Cheryl often mentions how she doesn't wish insects any harm (although she may not wish them any good, either). She might mention that when she is touring and finds a fly in her hotel room she will either call room service or go down to the vending machine to get something for the fly to eat while she is gone.