True Bugs

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True Bugs

Common families of terrestrial bugs in North America

Common families of aquatic bugs in North America

The true bugs are a large and diverse group of about 35,000 species of insects in the order Hemiptera. About 44 families of bugs occur in North America. About 25,000 species occur worldwide, on all continents except Antarctica and most islands. They range in length from 0.04 to 0.08 in (1 to 2 mm) to about 4 in (100 mm) or larger. Bugs typically have a flattened body, and their folded wings cross over their thorax and abdomen, giving a distinctive, cross like pattern.

Some species of true bugs are of great economic importance as pests of agricultural plants. A few species of bugs are vectors of important diseases of humans.

In popular usage, the word bug is often used to refer to non-hemipteran insects, and not only to true bugs. When used to refer to a species in the Hemiptera, the bug part of the name should be written separately, as in: stink bug, or milkweed bug. When used to refer to non-hemipteran insects, the bug part of the name should be used to form a single word, as in: ladybug (a family of beetles, order Coleoptera), or mealybug (scale insects, order Homoptera), or sowbug (Crustaceans in the order Isopoda, which are not even insects).

Biology of true bugs

The true bugs have an incomplete metamorphosis, characterized by three life-history stages: egg, nymph, and adult. The nymphs resemble the adults somewhat in form, but they are not capable of reproduction. Most North American bugs overwinter at the adult stage.

Bugs have two sets of wings. The forewings of most species of true bugs are rather tough and leathery towards their base, and membranous farther away. This unusual forewing structure is the origin of the Latin roots of the name for the order: Hemiptera, or half wing. The diagnostic, crossed-wing appearance of bugs at rest is also due to this unusual structure of the forewings, which form a well-defined ‘X’ when held flat over the back of the abdomen with the membranous tips overlapping. The hind wings are fully membranous, and are used for flying. Some types of true bugs have greatly reduced wings, and cannot fly.

The mouthparts of bugs are adapted for piercing and sucking. The mouthparts comprise a pointed, elongate structure known as a beak or rostrum that arises at the front of the head, and folds backwards, quite far underneath the body in some species. The beak is itself made up of specialized stylets used for piercing, and others develop channels used for actual feeding. Most species of bugs feed on plant juices, but a few are parasites of vertebrates, living on the animal’s surface and feeding on blood.

Most bugs have long, segmented antennae. Bugs have well developed, compound eyes, and adult bugs may have several simple eyes (or ocelli) as well. Many species of bugs have glands that give off a strongly scented, distasteful odor when the insect is disturbed.

Some species are quite brightly and boldly colored. Usually these bugs feed on plants that contain poisonous chemicals, which also occur in the bugs and render them distasteful or even toxic to potential predators. This type of boldly warning color scheme is known as aposematic coloration.

Most species of bugs are terrestrial, living on vegetation or in organic debris on the surface. Some species of bugs are specialized for living in aquatic habitats, occurring in the water column, or on the surface.

Common families of terrestrial bugs in North America

The most diverse family of bugs is the plant or leaf bugs (family Miridae), species of which can be found in terrestrial habitats world-wide. Almost all plant bugs feed on the juices of plants, some species causing important damages to agricultural crops. Important agricultural pests include the tarnished plant bug (Lygus lineolaris ), which feeds on a wide range of crop plants, the apple red bug (Lygidea mendax ), the cotton fleahopper (Psallus seriatus ), and the four-lined plant bug (Poecilocapsus lineatus ), a pest of currants and gooseberries. The garden fleahopper (Halticus bractatus ) is a common, jumping species in gardens and fields, which sometimes causes significant damages.

The assassin bugs (family Reduviidae) are mostly predators of other insects, although many will also give humans a painful bite if they are not handled with care, and a few are blood-sucking parasites. The blood-sucking conenose (Triatoma sanduisuga) sometimes occurs in houses in North America, and can inflict a particularly painful bite. In South America, other species in the genus Triatoma are the vectors of Chagas disease, a deadly disease of humans.

The ambush bugs (family Phymatidae) are also predators of other insects. Yellow species of ambush bugs are common hide-and-wait predators on species of goldenrod (Solidago spp.) throughout North America.

Seed bugs (family Lygaeidae) are a diverse group of mostly herbivorous bugs. Two common, attractive, red-and-black marked species are the small milkweed bug (Lygaeus kalmii ) and the large milkweed bug (Oncopeltus fasciatus ). The bright, aposematic coloration of these milkweed bugs is meant to deter potential predators, because these insects are distasteful due to alkaloid chemicals accumulated from their food of milkweed (Asclepias spp. ). The chinch bug (Blissus leucopterus ) is a serious agricultural pest, especially of wheat, corn, and other grains in the grass family, as well as urban lawn-grasses.

The lace bugs (family Tingidae) are herbivorous insects with distinctive, very attractive, finely reticulated patterns on their head, thorax, and wings. The chrysanthemum lace bug (Corythucha marmorata) is common in much of North America, feeding on various species in the aster family, and sometimes occurring in greenhouses.

The leaf-footed or coreid bugs (family Coreidae) are common, herbivorous insects. The squash bug (Anasa tristis) is a pest of pumpkin and squash crops, feeding on the leaves of these plants and causing them to droop and turn black. The box-elder bug (Leptocoris trivittatus) is an attractive, red-and-black colored insect that feeds on species of maples, but does not cause important damages.

The stink bugs (family Pentatomidae) are relatively large and common bugs that produce malodorous smells as a defensive response when they are roughly handled. Many of the stink bugs are brightly colored, for example, the harlequin bug (Murgantia histrionica ), an important pest of crops in the mustard family, such as cabbages, turnip, and radish.

Common families of aquatic bugs in North America

The water boatmen (family Corixidae) are common aquatic bugs that swim in the water column of lakes and ponds. The hind legs of water boatmen are oar-like in appearance, being long and flattened, and are used for underwater locomotion. Water boatmen do not have gills for the exchange of respiratory gases—they must breath head-first at the surface, although most species can carry a small bubble of air as they swim underwater. Most species of water boatmen are herbivorous, but some others are predators of other aquatic invertebrates. Water boatmen are an important food source for some species of wildlife, such as ducks. The water boatman (Arctocorixa alternata ) is a common and widespread species in North America.

The backswimmers (family Notonectidae) are also aquatic bugs. The especially elongate hind legs of these insects are used for swimming, which the backswimmers accomplish while in an upside-down position—hence, their common name. Backswimmers must breathe at the surface, but unlike the water boatmen these insects must break the surface abdomen first in order to obtain air. Backswimmers are predators of other aquatic invertebrates, and are themselves an important food for larger species. The back-swimmer (Notonecta undulata ) is a common and widespread species.

The giant water bugs (family Belostomatidae) include the world’s largest bugs, one species of which can attain a most-impressive length of 3.9 in (10 cm). Giant water bugs are oval in shape, with a rather flattened body, and are often a shiny brown color. The front legs are large and strong and are used to grasp their prey, which can include other aquatic insects, as well as small fish, tadpoles, and even frogs and salamanders. Giant water bugs sometimes leave their aquatic habitat and fly about, possibly for the purposes of dispersal. At such times these insects are attracted to lights, where they are sometimes known as electric light bugs. Giant water bugs can inflict a painful bite, and should be handled with care—these insects are sometimes known as toe-biters. The giant

KEY TERMS

Aposematic —Refers to a bright coloration of an animal, intended to draw the notice of a potential predator, and to warn of the dangers of toxicity or foul taste.

Incomplete metamorphosis —This is characterized by three life history stages: egg, nymph, and adult. The nymphs of true bugs resemble the adults in form, but they are not capable of reproduction.

Vector —Any agent, living or otherwise, that carries and transmits parasites and diseases.

water bug (Lethocerus americanus) is a widespread species in North America, and can reach a body length of more than 2.4 in (6 cm).

Water scorpions (family Nepidae) are another group of predacious aquatic bugs, with long, scissor-like front legs adapted for fiercely grasping their prey of insects and other creatures. Water scorpions can inflict a painful bite.

Water striders (family Gerridae) are semi-aquatic insects, living on the water surface. The long-legged body of water striders is suspended aloft by surface tension, made possible by the structure of their feet, which are covered with fine hairs that are not easily wetted. In parts of the southern United States, these insects are known as Jesus bugs because of their ability to walk on water. Water striders run and skate over the surface of ponds and lakeshores, hunting terrestrial arthropods that fall onto their two-dimensional habitat, and aquatic insects as they come to the surface to breathe. Water striders have odoriferous scent glands, which may be a deterrent against predation by fish. The water strider (Gerris remigis) occurs commonly throughout much of North America.

Bugs as a health hazard

Bed bugs (family Cimicidae) are wingless bugs with a body length of about 0.2 in (6 mm). Bed bugs feed by sucking the blood of birds or mammals. Various species will bite humans, and they can be serious pests in homes, hotels, and other places, especially the common bed bug (Cimex lectularius). Bed bugs come out at night, hiding during the day in cracks and crevices in walls and furniture. The bites of these insects are very irritating, but bed bugs are not known to be a vector of human diseases.

Chagas disease is common in parts of Central and South America, and is spread by blood-sucking bugs in the genus Triatoma, especially T. infestans. These are sometimes known as kissing bugs because of their tendency to bite near the mouth of their victims. Chagas disease is a debilitating malady of humans, and is caused by a pathogenic trypanosome, Trypanosoma cruzi, a type of parasitic protozoan that lives in the blood. Chagas disease is characterized by a recurring fever, and often a enfeebling inflammation of the heart muscles.