The world has around 20,000 species of grasshoppers and crickets. Australia has around 2,800 species.


A small number of insects and other bugs—about one per cent—are major pests. They are responsible for destroying crops and food, infesting livestock, damaging property and spreading disease.

Introduced Pests

When an animal species arrives in a new place, it often leaves behind the parasites, predators and other factors that kept its population numbers in check in its native home. A species that was not a pest in its native land can become a significant pest in a new location.

Unlike mammal, fish and bird introductions, most introduced bug species have reached Australia by accident. Bugs are small and can creep undetected onto boats and aircraft. They can also hitch rides in food, furniture, building equipment, plants and on animals—including humans.

Many of the bug species introduced to Australia are now well established and, in some cases, have become significant agricultural or urban pests.

Cockroaches from Europe and America were amongst the earliest invaders, arriving in Australia in the late 1700s and early 1800s. Australia’s 440 native species of cockroaches are the recyclers of the bush, eating dead plant material and returning nutrients to the soil, but the introduced species contaminate food and carry diseases such as salmonella and diphtheria.

Some recent arrivals that have created major problems for farmers and agriculturalists include the European Wasp, Fire Ant, Elm Leaf Beetle and Bumblebee.

Native Pests

Not all pests are introduced. The Queensland Fruit Fly is a native pest rather than an introduced one. It is now a major problem throughout eastern Australia due to the planting of fruit trees along the east coast and inland river systems. Fruit flies are not strong fliers, but are spread by infested fruit being carelessly discarded in a fruit growing area.

Biological Control

Sometimes bugs are deliberately employed as 'biocontrol' agents. This is the use of natural enemies to control non-native insects or plants, such as invasive weeds. The control species often comes from the original home of the pest species. It is more environmentally friendly than using pesticides or herbicides, but crucial research and testing is needed to make sure that the control species does not become a problem itself.

Wasps, Bees & Ants
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Elm Leaf Beetle, link to large image Elm Leaf Beetle

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