Order Hemiptera
Suborder Heteroptera
True bugs comprise around 6000 described species in Australia. The group is diverse, with species that have terrestrial, aquatic, semi-aquatic, arboreal (tree-dwelling), fossorial (burrowing) and parasitic lifestyles.
The Heteroptera can often be identified by the structure of the forewing. The basal (closer to the body) portion of the wing is hardened and opaque while the distal (further from the body) part is membranous. This type of wing is called a hemelytra. The subordinal name - Heteroptera- refers to this wing type: 'hetero', divided into two different parts + 'ptera', wing. However, not all species of Heteroptera have this wing form. Many are wingless, or have adult forms that lack wings.
The hindwings (when present) are all membranous.
Juveniles do not have fully developed wings and cannot fly.
Heteroptera have sucking mouthparts encased in a labium (lip) or rostrum (beak or proboscis) that is used to guide the mouthparts to the food source or prey.
Most of the Heteroptera feed on plants or plant material such as seeds, fruits or pollen. Many bugs are sap-suckers, using their mouth parts to pierce the outer surface of plant tissue to gain access to the phloem (tubes for transporting nutrients) of the plant.
The largest family of the Heteroptera, the Miridae, is extremely diverse. It contains mostly plant feeding bugs, some of which are agricultural pests. Miridae are generally delicate green to greenish-yellow coloured bugs of medium size that are often well camouflaged. Some of the Miridae mimic ants in body shape, colouration and movement, allowing them to avoid predation by appearing to be aggressive ants.
The most recognisable plant feeding Heteroptera are the stink bugs of the family Pentatomidae. Stink bugs are large and sometimes brightly coloured. The smell that one encounters when disturbing stink bugs is used as a defence against predators. A few of these bugs can be serious agricultural pests that cause damage to crops through their feeding, which can also allow for the transmission of pathogens (disease-causing agents) into the plant.
A related family, the Tessaratomidae, contains the common Bronze Orange Bugs (Musgraveia sulciventris ) that can be found in the garden congregating on citrus trees and other plants.
Fungus feeders can be found in a few families. Members of the Mirid subfamily Cylapinae are believed to feed on fungi, although more research is needed to confirm the exact nature of the relationship between the mirids and the fungi.
Members of the family Aradidae, or Flat Bugs, are often found in concealed locations of tree trunks or decaying logs where they feed on the fungal hyphae (threadlike elements that make up fungus), though some have been recorded from bird, rodent or termite nests.
Other plant-feeding Heteroptera feed on seeds. Their mouthparts are used to macerate (soften by wetting) the seed material before mixing it with saliva and sucking it up.
Members of the family Cydnidae burrow in the soil and feed on the roots of plants. These bugs are often mistaken for beetles (Order Coleoptera).
Predatory Heteroptera can be found in many families. Some are active predators, seeking out and attacking prey. Others adopt an ambush strategy, waiting for their prey to come to them.
The Reduviidae is a large group of predatory Heteroptera, commonly known as assassin bugs. Members of the assassin bug subfamily Peiratinae actively pursue their prey along the ground or on vegetation, grabbing them with their forelegs before immobilising them. Another subfamily of assassin bugs, the Emesinae, has members that adopt a different predatory strategy. They live in spider webs and steal the trapped prey of the spider or live off the food collected by the spider.
Some other assassin bugs live on the outside of termite nests and stick their mouthparts through the walls of the nest to catch their prey. A small number of assassin bugs suck the blood of vertebrates. In Central and South America some species of blood-sucking assassin bugs are a vector of Chagas' Disease (caused by a blood borne protozoan), but in Australia they are not known to transfer any diseases.
Aquatic and semi-aquatic bugs are mostly all predacious, with the exception of the family Corixiidae which feed primarily on algae. Aquatic bugs such as the Water Scorpions are large predators that like to ambush their prey. They have raptorial forelegs which allow them to seize small aquatic invertebrates or fish that pass close by.
One of the most often encountered families of semi-aquatic bugs are the Gerridae (Water Striders). They are often seen floating lazily or 'skating' across areas of still water such as ponds. Water Striders wait for insects or other invertebrates to fall on the surface of the water and then 'skate' over and attack by piercing the body of the prey with their mouthparts. Gerridae are one of the few insect groups to successfully use the ocean as a habitat.
Less common are the predacious Toad Bugs of the family Gelastocoridae which inhabit mostly areas of wet soil or sand close to streams. These small bugs have wings but do not fly. Instead they get around by small hopping movements.
Backswimmers (Family Notonectidae) are fully aquatic bugs that swim upside down just below the water's surface. From time to time backswimmers will surface to take in a fresh supply of air. They readily seize prey that has fallen onto the surface of the water or which passes nearby. They will even eat tadpoles and tiny fish.
Parasitism and klepto-parasitism are also found in the Heteroptera. Parasitism is where an organism lives in or on a host without benefiting the host. Klepto-parasitism is where an organism scavenges or steals food from another organism.
Parasitic bugs of the family Polyctenidae are know as bat bugs and live permanently on the bodies of bats. They congregate in areas the bats find hard to groom and suck the blood of the bat.
Klepto-parasitic Miridae live on the leaves of carnivorous plants (of the genera Byblis and Drosera), stealing the prey trapped in the sticky hairs on the leaves. They avoid being trapped themselves through the use of specialised structures on their feet.
Humans and other mammals suffer parasitism from bugs of the family Cimicidae, the most familiar of which is the Bed Bug. Bed Bugs live in the recesses and concealed locations of human habitations, emerging at night to feed on sleeping humans. Advances in hygiene and cleanliness in the last century have seen a decline in the incidence of Bed Bugs in Australia, though they can still be found in some dwellings where hygiene is not a priority.
Copyright © Australian Museum, 2003
This page: http://www.amonline.net.au/factsheets/true_bugs.htm
