What the upper and lower lips of biting and chewing insect pests called?

The upper lip of biting and chewing insect pests is called the "labrum," while the lower lip is referred to as the "labium." These structures play crucial roles in feeding by helping to manipulate food and direct it towards the mandibles, which are the primary chewing organs. Together, the labrum and labium assist in the insect's ability to bite and chew effectively.