A short time since, some friends drinking tea one summer evening at their residence near Maidenhead, with all the windows of the drawing-room open, there suddenly burst in a host of small flies, which covered the table and the furniture; every one of these emitted a sparklet of light, pure and intense like that of the glow-worm; and altogether they formed, for a few minutes, a spectacle as beautiful, as we should imagine it to be, in the British isles, uncommon.
Source: wiktionary