The "buzz" can be made with repeated chromatic melodic patterns, keeping closely within a limited range of pitches, such as C CNoNo D DNoNo and back again. The "swarm" effect can come from overlapping these with similar patterns that start at different places within the octave - for example, F FNoNo G GNoNo or GNoNo A ANoNo B. These can be played on xylophones, guitars and keyboards and any available orchestral instruments.
KS 3-5 More experienced players can try to fit these "cells" into 6-note units, reflecting the hexagonal structure of the wasps' nest. Experiment with crescendo and diminuendo, to recreate the feeling of a moving mass of insects. Then listen to the opening of Vaughan Williams's "Wasps" overture, and hear how it works with an entire orchestra.