Many people use the word 'bug' for any sort of insect, or for any strange creepy crawly for that matter. However in the insect world, the word bug applies to a particular group of insects, the Order Hemiptera, that have special mouthparts designed for sucking up liquids. To avoid this confusion with names, these insects are sometimes called sucking bugs or true bugs.
This is a very large group of insects, probably with more than 10000 Australian species. It includes some very different looking insects.
Many are important pests of crops, especially aphids, scale insects and mealybugs. Some like cicadas are conspicuous because of their ability to sing. Related to cicadas are leaf and planthoppers. Many of these also communicate with sound, but transmitted through the plants on which they live.
True bugs also include the familiar stink and shield bugs and the predatory assassin bugs. There are also several groups of sucking bugs that live in freshwater such as backswimmers, waterboatman and water scorpions.
True bugs are very diverse in form and habit, ranging from the plant sucking, tiny, rounded wingless aphids, stem hugging Lantana Treehoppers and Mallotus Harlequin Bug to the predatory, aquatic Water Scorpion (see images below).
Lantana treehopper, Aconophora compressa.
Mallotus Harlequin Bug, Cantao parentum.
Water scorpion, Laccotrephes tristis.
Eucalypt Planthoppers, Platybrachys decemmacula (Eurybrachyidae), are common on eucalypt tree trunks in open forest and woodland. The nymph has a pair of long, upright filaments at the tip of their abdomen.
A beautiful female Peltocopta crassiventris (Tessaratomidae).
The most characteristic feature of sucking bugs is their mouthparts. They usually consist of an elongated, tubular proboscis, or rostrum, which is designed to pierce plant or animal tissues and suck up fluids. When not in use, the rostrum is folded beneath the head and points towards the rear of the insect.
Most sucking bugs have two pairs of wings, but these can be variable. In many such as aphids, planthoppers and cicadas, both pairs of wings are membranous, have a network of veins, and are held roof-wise over the body. In others, such as stink bugs and assassin bugs, each front wing has a thickened base and a membranous tip which has a few wing veins. These half thickened wings are called hemielytra and are a bit like the wing-covers of beetles. They help protect the more delicate hind wings that are folded underneath.
The most bizarre sucking bugs are the scale insects and their relatives. Adult females have very reduced bodies. They have no wings and sometimes no legs. They often spend most of their lives glued to the one spot on a plant with their mouthparts inserted. Many even secrete a distinctive shell or scale that completely covers the body.
Many sucking bugs have a triangular structure in the middle of the back called the 'scutellum'. This is often shield-shaped or may be enlarged. Sucking bugs belong to the Order Hemiptera. There are 88,000 described species of sucking bug in the world, with over 5,000 described for Australia. Almost the same number remains to be named.
Mouthparts in the form of an elongated rostrum are the most characteristic feature of sucking bugs, as seen in this assassin bug (top) and cicada (above). When not being used for feeding the rostrum is folded underneath the head.
The wings are held roof-wise over the body in this bladder cicada, Glaucopsaltria sp. (Cicadidae).
Many sucking bugs have a prominent scutellum, a triangular structure in the middle of the back, seen in this brightly coloured male Peltocopta crassiventris (Tessaratomidae).
Sucking bugs all feed on liquid food through the rostrum beneath the head. The great majority of species feed on plant juices, which they obtain by inserting the tip of their rostrum into living plants. A few sucking bugs are predatory (e.g. assassin bugs) and suck juices from other insects, while some, such as bed bugs, even suck blood from vertebrate animals.
Sucking bugs undergo gradual metamorphosis passing through a number of nymphal stages before maturity.
These nymphs of Peltocopta crassiventris (Tessaratomidae) have just hatched from a mass of eggs.
Some sucking bugs, like scale insects, lack wings and live a sedentary life attached to their host plants feeding on plant fluids. Others, including leaf and plant hoppers, have strong back legs modified for jumping.
The nymphs and adults of the introduced biocontrol agent, the Lantana Treehopper, Aconophora compressa, are capable of jumping.
Some bugs show maternal care, guarding their eggs to protect them from parasites and predators. Peltocopta crassiventris goes a step further and carries her newly hatched nymphs beneath her abdomen.
Cicadas are a familiar group of sucking bugs because of their conspicuous summer songs. However, many other sucking bugs communicate by sound vibrations transmitted through their host plants.