Complex sentence: Because of their small sizes, fairyflies may sometimes be mistaken for members of the families Aphelinidae and Trichogrammatidae, but members of these other families can readily be distinguished by having much shorter antennae.
Split into simpler sentences: Because of their small sizes, fairyflies may sometimes be mistaken for members of the families Aphelinidae and Trichogrammatidae. But members of these other families can readily be distinguished by having much shorter antennae.