Complex sentence: Flies in the family Pyrgotidae are endoparasitoids of these and related beetles; the females pursue the beetles in flight, laying an egg on the beetle's back under the elytra where the beetle cannot reach it.
Split into simpler sentences: Flies in the family Pyrgotidae are endoparasitoids of these and related beetles. The females pursue the beetles in flight, laying an egg on the beetle's back under the elytra where the beetle cannot reach it.