The labrum (fig,.
The actual piercing organs are the mandibles, while the upper lip or labrum forms a sucking tube.
The maxillae are not piercing organs, and their function is to protect the mandibles and labrum and separate the hairs or feathers of the host.
Maxillary and labial palpi are also present, and the latter, together with the labrum or lower lip, form the rostrum.
A, Labium; b, maxilla; c, labrum; d, mandible.
The Curculionidae, or weevils (q.v.), comprising 23,000 species, are by far the largest family of the group. The maxillary palps are short and rigid, and there is no distinct labrum, while the feelers are usually of an "elbowed" form, the basal segment being very elongate (figs.
Below this comes the front, and then the face or clypeus, to which a very distinct upper lip (labrum) is usually jointed.
Behind the labrum arises a process - the epipharynx - which in some blood-sucking insects becomes a formidable piercing-organ.
In front or above the mouth is bounded by the labrum, while the mandibles and first maxillae lie on either side of it.
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).
The labrum and clypeus are developed as a single prolongation of the oral piece, not as a pair of appendages.
Comstock and C. Kochi believe that the labrum belongs to it,, The appendages of the posterior three or trophal segments become the parts of the mouth.
- Cross section of Embryo of German Cockroach (Phyllo- labrum represent, as already said, an unpaired median outgrowth dromia).
A, anus; Abx 1 Abx 11, appendage of 1st and of 11th abdominal segments; Ans, anal piece=telson or 12th abdominal segment; Ant, antenna; De, deuterencephalon; Md, mandible; Mx1, first maxilla; Mx2, second maxilla or labium; 0, mouth; Obcl, rudimentary labrum and clypeus; Pre, protencephalon; St t, Stu), stigmata i and io; Terg, tergite; Thx1, appendage of first thoracic segment; Tre, tritencephalon; Ul, a thickening at hinder margin of the mouth.
On the 1 A pair of round tubercles on the labrum (camerostome or hypostoma) of several species of Trilobites has been described and held to be a pair of eyes (22).
The tip of the proboscis is armed with a complicated series of chitinous teeth and rasps, by means of which the fly is enabled to pierce the skin of its victim; as usual in Diptera the organ is closed on the upper side by the labrum, or upper lip, and contains the hypopharynx or common outlet of the paired salivary glands, which are situated in the abdomen.
- A, Front of head of Sawfly (Pachynematus); a, labrum; b, clypeus; c, vertex; d, d, antennal cavities.
The Nepidae breathe by means of a pair of long, grooved tail processes (really out-growths c, labrum; d, epipharynx.
The Corixidae are small flattened water-bugs, with very short unjointed beak, the labrum being enclosed within the second From Marlatt, Bull.
Pieces of bone, stone, shell, &c., were worn as ornaments in the lip (Latin, labrum) or cheek by Eskimo, Tlinkit, Nahuatlas and tribes on the Brazilian coast.
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.
1, labrum, or upper lip.
Silurian, head showing the labrum and Lanark.
In parasitic bloodsucking forms the mandibles often have the shape of piercing stylets, and are enclosed in a tubular proboscis formed by the union of the upper lip (labrum) with the lower lip (hypostome or paragnatha).
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.