Fam. 17. Polyctenidae.—Proboscis-sheath three-jointed, tarsi four-jointed, antennae four-jointed. Tegmina quite short, of one consistence.—The four or five anomalous species forming this family are parasites on bats of the genus Molossus, and have been found in both the Eastern and Western hemispheres. Westwood, who first described them,[[493]] treated them as aberrant Anoplura or Lice, but there do not appear to be any sufficient grounds for removing these parasites from Hemiptera-Heteroptera. The condition of their alar organs reminds one of what exists in Cimex and Aëpophilus, and the mouth is not known to possess any very peculiar structure. We have had no opportunity of making a thorough examination of Polyctenes, and therefore speak with some diffidence.
Fig. 274—Helopeltis sp. East India.
Fig. 275—Section of a stem with egg of a Capsid bug allied to Helopeltis (Moesa-blight). × 58. (After Dudgeon.)
Fam. 18. Capsidae.—Moderate-sized or small bugs, of delicate consistence, without ocelli; the elytra and wings usually large in proportion to the body, the former with two cells (occasionally only one) in the membrane. Antennae four-jointed, the second joint usually very long, the terminal two more slender than the others. The proboscis not received in a groove. Scutellum exposed, moderately large. Tarsi three-jointed. Female with an ovipositor capable of exsertion.—This family is one of the most extensive of the Hemiptera; we have about 170 species in Britain, where they are most abundant in the south. The exotic species have been but little collected. Their colours are usually delicate rather than vivid, and are never metallic. They frequent plants of all kinds, and many of them skip by the aid of their wings with great agility in the sunshine. The majority probably suck the juices of the plants, but some are known to prey on other Insects. The species of the Indian genus Helopeltis (Fig. 274) are remarkable by possessing a knobbed spine projecting straight up from the scutellum, making the individual look as if it were a specimen with a pin through it: they attack the tea-plant and do considerable damage. They are known as Mosquito-blight. The egg is of comparatively large size, and is placed by the bug in the stems of the tea-plant, but attached to one end of the egg are two long slender threads that project externally. A similar egg (Fig. 275) and method of oviposition have been described by Mr. Dudgeon as occurring in another species of Capsidae, called Moesa-blight, in India.[[494]]
Fam. 19. Saldidae.—Head short and broad, with large, prominent eyes. Ocelli present. Proboscis not applied to under surface of head or breast in repose. Scutellum large, not covered. Elytra covering the upper surface of the abdomen, formed of three distinct parts. Tarsi three-jointed.—These little bugs run with velocity over mud in damp places, or live in wet moss; some of them can jump; they are all of dark or obscure colour. There are only three genera: Salda, of which we have numerous British species, being the principal one.
Series 2. Cryptocerata.
The remaining families of Heteroptera are of aquatic habits, and form in nearly all works a separate division called Hemiptera Cryptocerata (or Hydrocorisae, or Hydrocores), distinguished by the antennae being apparently absent; they are, however, really present, being situate on the under side of the head, to which they are closely pressed, or in some cases placed in a pocket in front of each eye. There are six of these families. Schiödte is doubtless correct in treating this division as an unnatural one; it is, however, generally adopted, and is convenient for the purposes of nomenclature and arrangement.
Fam. 20. Galgulidae or Pelogonidae.—Form short and broad; head very broad, with prominent eyes, ocelli present. Hind legs thin, formed for running.—The Insects of this family are but little known; they are only sub-aquatic in habits, frequenting damp places at the margins of streams and waters. The presence of ocelli distinguishes them from other water-bugs, with which indeed the Galgulidae appear to be but little related. There are only about twenty species of the family known. We possess none in Britain; but one, Pelogonus marginatus, occurs in South Europe. The other members of the family are very widely scattered over the surface of the earth.