Mouth suctorial, beak-shaped, consisting of a jointed rostrum, composed of the elongated labium, which forms a jointed, tubular sheath for the bristle-shaped, styliform mandibles and maxilla. Eyes compound, usually with ocelli as well. Two pairs of wings in most; sometimes wanting. Pupa generally active.
The Hemiptera live upon the juices of plants or animals, which they are enabled to obtain by means of the suctorial rostrum.
Fig, 181. - Hemiptera. Bean Aphis (Aphisfabae), winged male and wingless female.
* The Coccidae, amongst the Hemiptera, undergo a complete metamorphosis. In certain of the Hemiptera and Orthoptera the adult is apterous, and in these cases there cannot be said to be any metamorphosis, since the larvae differ from the adult only in size, in having fewer joints to the antennae, and in having a smaller number of facets in each of the compound eyes.
The order is divided into the following three sub-orders:
The anterior pair of wings of the same texture throughout (membranous); the mouth turned backwards, so that the beak springs from the back of the head. The wings fold over one another when the insect is at rest. There are ocelli between the compound eyes, and the antennae are small and composed of few joints. The females often have an ovipositor of three toothed blades. In this section are the Aphides, the Scale Insects (Coccidae), the Cicadas, the Lantern-flies (Fulgora), etc. As typical examples of the Homoptera may be taken the Cicadas (fig. 182, D), the males of which are well known for their power of emitting a musical note or chirp. The Plant-lice or Aphides (fig. 181) live upon the juices of plants, an enormous number of species being known. They may possess two pairs of membranous wings, or none, and they give birth to innumerable young in the summer months by a process of parthenogenesis. The singular Scale-insects (Coccidae) have the males winged, whilst the females are deformed, often scale-like, and devoid of wings. The dried female of the Cochineal Insect (Coccus cacti) constitutes the cochineal of commerce, and the Coccus lacca yields shell-lac.
Fig. 182. - A, Thrips, enlarged; B, Nepa cinerea, enlarged; C, Cicada Anglica, the wings on the right side of the body being omitted ; D, Larva of the same ; E, Pupa of the same. (Figs. C, D, and E are after Westwood.)
Anterior wings membranous near their apices, but chitinous towards the base (hemelytra); the rostrum springing from the front of the head. The inner margins of the wings are straight or contiguous. The antennae are moderate in size, and composed of a few large joints. They are divided into the two groups of the Hydrocorisae (Water-bugs) and Geocorisae (Land-bugs), according as they are aquatic or mainly terrestrial in their habits. Amongst well-known members of this group may be mentioned the Forest-bugs and Field-bugs (Pentatoma, and its allies), the Bed-bug (Cimex lectularius), the Boat-fly (Notonecta), the Water-scorpions (Nepa, fig. 182, B), and the Water-spiders (Hydrometra).
Thysanoptera. - Mouth with mandibles and maxillae, furnished with palpi. The wings with few or no ner-vures, fringed. In this suborder are only the little insects which form the genus Thrips (fig. 182, A), and some allied forms. They live upon plants, and differ from the typical Hemiptera both in the structure of the wings, and in the fact that the beak-like rostrum really contains palpate mandibles and maxillae.