Orthoptera: grasshoppers and locusts
For more information on plague locusts visit the Australian Plague Locust Commissiontralian Plague Locust Commission

Characteristics
Grasshoppers, crickets, katydids and locusts all belong to the order Orthoptera which means 'straight wings'. Most are easily recognisable by their hind legs, which are usually enlarged for jumping. They are often easily seen jumping away when disturbed or heard 'singing' at night. They are mainly medium to large insects with some species in Australia growing to a length of 10 centimetres. There are about 3000 species in Australia and all can be distinguished from other insects by the following features:

• 2 pairs of wings. The forewings are narrower than the hind wings and hardened or leathery at the base. They are held roof-like overlapping the abdomen at rest. The hind wing is membranous and held folded fan-like under the forewings when at rest

• Mandibulate mouthparts

• Large compound eyes

• Antennae may be short to very long depending on the species. Grasshoppers have relatively short antennae while crickets and katydids generally have long antennae

• Hind legs are enlarged and modified for jumping

The general appearance of this order makes it difficult to confuse with other insects. The young of Orthoptera look like small wingless adults. Many orthopterans can produce sound by rubbing their legs, wings or abdomen together. It is predominantly males that produce these sounds to attract females.

Life Cycle
Orthopterans develop by incomplete metamorphosis. The majority of orthopterans lay their eggs in the ground or on vegetation. The eggs hatch and the young nymphs resemble adults but lack wings and at this stage are often called hoppers. Through successive moults the nymphs develop wings buds until their final moult into a mature adult with fully developed wings. The number of moults varies between species but grasshoppers may have up to 6 while crickets may have up to 10. Growth is also very variable and may take anywhere from a few weeks to many months depending on such things as food availability and weather conditions.

Siliquofera grandis

Feeding
Most orthopterans are herbivorous feeding on a variety of plant materials including roots. Most short-horned grasshoppers feed on grasses while many long-horned grasshoppers (such as katydids) and crickets tend to be more omnivorous. Some species are even scavengers or predators.

Habitat
Orthopterans are found in all terrestrial habitats across Australia. They are commonly in association with vegetation, from ground level to the canopy, in burrows in the soil or moving across open ground, depending on the species. Most are active during the day, feeding on vegetation and others such as mole crickets spend most of their time in underground burrows. Orthopterans are usually found singularly or in small numbers, however a few species sometimes increase in numbers forming plagues that can cause much damage and huge crop losses, such as the Australian plague locust pictured below.