Complex sentence: These first-instar larvae have stemmata (simple, single-lens eyes) and they enter their hosts by secreting enzymes that soften the cuticle, usually in the abdominal region of the host.
Split into simpler sentences: These first-instar larvae have stemmata (simple, single-lens eyes). The larvae enter their hosts by secreting enzymes that soften the cuticle, usually in the abdominal region of the host.