Trying to identify a short story from some long-forgotten collection with multiple authors. All I really remember is a man attempting to swat a fly that landed on him...when a blue flame shoots out of it and it gets away.
Excited, he reached forward again, but as his plucking fingers approached, the fly rose smoothly in a vertical ascent, lifting a pyramid of taut strands and tearing a gap in the web as easily as a flipped stone. The man was alert, however. His cupped hand, nervously swift, snapped over the insect, and he gave a satisfied grunt.
But the captive buzzed in his grasp with a furious vitality that appalled him, and he yelped as a searing, slashing pain scalded the sensitive palm. Involuntarily he relaxed his grip. There was a streak of electric blue as his prize soared, glinting in the sun. For an instant he saw that odd glowworm tail light, a dazzling spark against the darker sky, then nothing.