Parts of Mouth

a) Labrum: Labrum or upper lip is a broad lobe that covers the mandibles and closes the mouth cavity from the upper front. It helps to pull the food into mouth.

b)Mandibles: Mandibles are the anterior part and lie directly behind the labrum as the appendages of the second post-oral segment. Mandibles move sideways, can bite off and chew food particles.

c) Maxillae: These lie directly behind the mandibles and are the appendages of the third post oral segment. It can be divided into following well marked parts:

i. Cardo: The triangular basal sclerite attached to the head capsule that serves as a hinge for the movement of the remainder of the maxillae.

ii. Stipes: It is the central portion of the body of the maxillae and is situated above the cardo and is the basis for the remaining of the maxillae.

Iii. Galea: It is the outer or lateral lobe articulating at the end of the stipes and bears a cap of sense organs.

iv. Lacinia: It is the inner or mesal lobe and is usually mandible like in form with a series of spines or teeth along its mesal edge.

v. Palpus: It is the antennae like segmented appendage which arises from the lateral side of the stipes and is sensory in function.

d) Labium: It lies posterior the maxillae and is formed by the fusion of a pair of appendages serially homologous with the maxillae. It is divided into two primary portions: a basal postmentum and distal prementum.

I. Postmentum: It is the basal region of labium and hinges with the head membranes.

ii. Prementum: It is the apical region of the labium and includes various lobes and processes. The apical portion of prementum frequently forms a sort of tongue and is called ligula.

e) Epypharynx: It is present on inner and posterior side of labrum. Epipharynx is a sensory area believed to contain end organs of taste.

f) Hypopharynx: Hypopharynx is a short tongue like structure located immediately above the labium and between the maxillae. In most insects, the ducts from salivary glands open on or near the hypopharynx. In a few primitive insects, a pair of lateral lobes occurs with the median lingua of hypopharynx and is called superlinguae.