Complex sentence: Typically, Tachinid larvae are endoparasites (internal parasites) of caterpillars of butterflies and moths, or the eruciform larvae of sawflies, but some species attack adult beetles and some attack beetle larvae.
Split into simpler sentences: Typically, Tachinid larvae are endoparasites (internal parasites) of caterpillars of butterflies and moths, or the eruciform larvae of sawflies. However, some species attack adult beetles and some attack beetle larvae.