HETEROPTERAN

a member of the insect order Heteroptera, which comprises the "true bugs." The order is divided into three suborders: the aquatic Hydrocorisae (giant water bugs, water boatmen, water scorpions, and backswimmers), the semi-aquatic Amphibicorisae (shore bugs and water striders), and the terrestrial Geocorisae (bedbugs, stinkbugs, assassin bugs, lace bugs, fire bugs, and plant bugs). Members of the order are found on all land masses except Antarctica and in climates from tropical to arctic, although the majority of the 30,000 known species live in tropical areas. Unique to this order are certain pelagic (ocean-going) water striders (family Gerridae), which may not touch land for generations. Owing to their fragility there is only a poor fossil record of the heteropteran order. The earliest heteropteran fossils are from the Permian Period of Australia (286 to 245 million years ago). Heteropterans range in size from under one millimetre (0.04 inch) to more than 100 mm. They are distinguished from other insects by the presence of a pair of simple eyes in front of and above the compound eyes, a hardened gula (the area below the mouthparts), and an "X" formed on the back by the overlapped wings. They live chiefly on plant or animal juices. As in other insects, the head contains the organs of sight, sound, and smell; the thorax serves as the point of attachment for the legs and wings; and the abdomen contains reproductive organs. The two pairs of wings differ. The forewings have a leathery basal half and a membranous tip; the hindwings are thin and membranelike throughout. In some species the legs are adapted for jumping, swimming, or grasping. In aquatic adaptations the limb may be flattened, but in some cases it has developed a fringe of long hairs which spread out to present a greater surface during each swimming stroke. The mouthparts are adapted to piercing and sucking; the mandibles and maxillae have evolved into stylets that lie within a troughlike labium. When these mouthparts are joined and extended they form two tubes. Food is ingested through the anterior tube, or canal; the posterior canal is the passage through which digestive juices, often containing killing or stunning toxins, reach the food source. In terrestrial forms, respiration takes place through 10 pairs of holes (spiracles) in the body wall. Aquatic forms have various modifications of this system. In some the spiracles are surrounded by water repellent (hydrofuge) hairs and act as storage chambers while the insect is below the surface. Plastron respiration occurs in the Naucoridae; air is held in a series of grooves (the plastron) radiating out from a spiracle. As long as the water is well oxygenated these bugs do not need to surface, as the plastron can absorb as much dissolved oxygen as is necessary. Water striders and their relatives actually walk on the water's surface-tension film. The long slender legs assure widely spaced points of contact, and the body is very slight. A dense hydrofuge coat protects the body from becoming waterlogged during submersion. Terrestrial heteropterans occupy a great variety of habitats. Some live on plants, some under rocks or bark, and some in the ground. Members of certain families (e.g., Nabidae) live in spider webs, subsisting on trapped insects or, occasionally, the spider. Semiaquatic forms generally are associated with quiet waters, although some species are adapted for living in rapids. The Polyctenidae, which live in bat nests, and the Termitaphididae, which live in termite nests, are wingless. Heteropterans are generally not social insects. Predatory species disperse soon after hatching, as opportunities to feed are greater away from competitors. Nymphal stages of plant-eating (phytophagous) species may remain in a group for a time, as they usually hatch on their preferred food plant. The diets of predatory forms vary widely. Members of the suborder Amphibicorisae prey on worms, small arthropods, and plankton. Many terrestrial species prey on other insects, including other heteropterans. Aerial hunters generally ambush their victims, as they are not rapid enough fliers to pursue many prey species. They paralyze the prey with a salivary secretion. A few forms, including bedbugs, (Cimicidae), bat bugs, and some assassin bugs (Reduviidae) subsist on avian or mammalian blood. The Termitaphididae live only on the fungi growing in certain termite nests. These bugs secrete from pores on their backs a substance that is eaten in turn by the termites. Eggs may be laid in groups or singly, and they may hatch shortly after being laid, although many species overwinter in the egg. The hatched young typically have five nymphal stages, or instars, going through five molts in a gradual metamorphosis to the adult form. The nymphs lack the rigid protective exoskeleton of the adult but as a result are able to expand and thus take in greater quantitites of food. Nymphs, which lack wings, generally rely on motionlessness or camouflage to protect them from predators. The wings only become functional after the final molt into the adult form. Many heteropterans produce sound with various bodily parts (stridulating organs). These sounds may have significance in mating behaviour, but they are generally not loud enough to be easily noticed by humans. Heteropterans are important to man in several ways. Some, such as plant bugs (Miridae) and stinkbugs (Pentatomidae), may damage crops while feeding. On the other hand, certain predatory heteropterans are used to control infestations of other crop-damaging insects. Some, like the bedbugs, are biting pests, and still other may serve as carriers of various diseases. any member of the insect order Heteroptera, which comprises the so-called true bugs. (Some authorities use the name Hemiptera; others consider both the heteropterans and the homopterans to be suborders of the Hemiptera.) This large group of insects, consisting of about 30,000 species, can be recognized by an X-shaped design on the back, which is formed by the wings at rest. A combination of features-sucking mouthparts adapted to pierce plant or animal tissues and a hardened gula (underside of the head)-separate the heteropterans from all other insect orders. Although most species of Heteroptera are terrestrial, a few are aquatic. Some species, which feed on plant juices, are serious pests of cultivated crops; other species are predacious and benefit man by destroying various pests. There also are heteropterans that act as carriers of disease. Heteropterans can be divided into three large groups on the basis of general habitat: the water-dwelling Hydrocorisae (water boatmen, back swimmers, water scorpions, giant water bugs, and creeping water bugs); the surface-swimming and shore-dwelling Amphibicorisae (water striders, marsh and water treaders, shore bugs, and velvet water bugs); and the Geocorisae, a large group of land bugs (plant bugs, bedbugs, assassin bugs, anthocorid bugs, lace bugs, ambush bugs, stinkbugs, burrower bugs, stilt bugs, and fire bugs). Additional reading W.S. Blatchley, Heteroptera of Eastern North America (1926), introduction to Heteroptera, especially those of eastern North America; E.A. Butler, A Biology of the British Hemiptera-Heteroptera (1923), classic work with biological data; W.E. China and N.C.E. Miller, "Checklist and Keys to the Families and Subfamilies of the Hemiptera-Heteroptera," Bull. Br. Mus. (Nat. Hist.) Ent., 8:1-45 (1959), phylogenetic dendrogram and assignment of names, includes a bibliography of source studies; R.H. Cobben, Evolutionary Trends in Heteroptera, Part 1, Eggs: Architecture of the Shell, Gross Embryology and Eclosion (1968), structural and developmental details with interpretive comments; W.L. Distant, Rhynchota, in Fauna of British India, 5 vol. (1902-18, reprinted 1977), a study of Asian Heteroptera, and Biologia Centrali Americana Insecta, vol. 1, Rhynchota Heteroptera (1881-1909), a classic study of tropical American fauna; P.T. Haskell, Insect Sounds (1961), readable, though in places technical, introduction to a fascinating topic; H.B. Hungerford, "The Biology and Ecology of Aquatic and Semiaquatic Hemiptera," Kans. Univ. Sci. Bull., 11:1-265 (1919), classic and basic study; N.C.E. Miller, The Biology of the Heteroptera, 2nd rev. ed. (1971); H.M. Parshley, A Bibliography of North American Hemiptera-Heteroptera (1925); T.R.E. Southwood and D. Leston, Land and Water Bugs of the British Isles (1959), keys and notes through species; W. Stichel, Illustrierte Bestimmungstabellen der Wanzen, 2, Europa (1955-62), four volumes with keys to European species and a checklist for Palearctic Region; R.L. Usinger, Monograph of Cimicidae (Hemiptera-Heteroptera), vol. 7 (1966), incorporates modern methodology in monographic study of important bedbugs; E.P. Van Duzee, Catalogue of the Hemiptera of America North of Mexico (1917), important list and literature summary of North American Heteroptera; H. Weber, Biologie der Hemipteren (1930, reprinted 1968), important source for original and compiled information. Richard Charles Froeschner