Mandibles fused into a piercer; first maxillae developed as piercers; palps of both pairs of maxillae present; hypopharynx wanting.
A median process, known as the hypopharynx or tongue, arises from the floor of the mouth in front of the labium, and becomes most variously developed or specialized in different insects.
Next the larvae make their way into the connective tissue in the pro-thorax, and ultimately bore a channel into the base of the piercing apparatus and come to rest between the hypopharynx and the labium.
The sucking tongue of the Hymenoptera has often been compared with the hypopharynx of other insects.
Mandibles rarely present, adapted for piercing; first maxillae with palps; second maxillae forming with hypopharynx a suctorial proboscis.
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.
Folsom looks on the hypopharynx as a secondary Obcl development.
In front of the rostrum and the piercers lies the pointed flexible labrum and within its base a small hypopharynx (fig.
Ileymons, the hypopharynx represents the sterna of all the jaw-bearing somites, but other students consider that it belongs to the mandibular and first maxillary segments, or entirely to the segment of the first maxillae.