Write about the mandibles in cockroaches.

Mouth of a cockroach:

1. The mouth of a cockroach is Hypognathous i.e the head is vertical and at right angles to the long axis of the body and mouthparts are ventrally located and projected downwards.
2. The mouth parts of the cockroaches include –

• Labrum or the upper lip
• Mandibles or the true jaws
• Maxilla or additional jaws
• Labium or lower lip
• Hypopharynx or tongue

Mandibles of cockroach:

1. They are also called true jaws.
2. They are positioned below the labium on either side of the mouth.
3. Each mandible is a dark coloured, hard structure covered by an exoskeleton.
4. It is joined with the head capsule by strong muscles at one end.
5. The free end has a large number of teeth-like projections.
6. The two mandibles work in a sideway fashion for cutting and crushing the food.