According to Hinds they feed chiefly on the green tissues, which " are punctured by the piercing mouth-parts and the sap withdrawn by suction.
The structure of the mouth-parts is different from that seen in any other insects.
It is now held that the parasite enters the blood of man through the piercing mouth-parts at the time of biting.
The other structural characters of the Order may be briefly summarized as: - mouth-parts adapted for piercing and sucking, or for suction alone, and consisting of a proboscis formed of the labium, and enclosing modifications of the other usual parts of the mouth, some of which, however, may be wanting; a thorax fused into a single mass; and legs with five-jointed tarsi.
The mouth parts are well developed, consisting of an upper lip, powerful mandibles, maxillae with three-jointed palpi, and a deeply quadrifid labium or lower lip with three-jointed labial palpi.