The term labrum is used in zoology, of a lip or lip-like part; in entomology it is applied specifically to the upper lip of an insect, the lower lip being termed labium.
There is usually a distinct labrum (fig.
The labrum and clypeus are developed as a single prolongation of the oral piece, not as a pair of appendages.
Behind the labrum arises a process - the epipharynx - which in some blood-sucking insects becomes a formidable piercing-organ.
The mouth is overhung by a large labrum or upper lip, and the integument of the dorsal surface of the body forms a more or less definite dorsal shield.
The actual piercing organs are the mandibles, while the upper lip or labrum forms a sucking tube.
In front of the rostrum and the piercers lies the pointed flexible labrum and within its base a small hypopharynx (fig.
He insists on the value of the upper lip or labrum for generic distinction, and as an aid in affiliating larval forms of different stages to their several species.
The Corixidae are small flattened water-bugs, with very short unjointed beak, the labrum being enclosed within the second From Marlatt, Bull.
Ia, frons; b, clypeus (the pointed labrum beneath it); II, mandible; III, first maxilla; (a, base; b, sheath; c, piercer), III', inner view of sheath; IV, second maxillae forming rostrum (b, mentum; c, ligula).