A small number of insects and other bugsabout one per centare major
pests. They are responsible for destroying crops and food, infesting livestock,
damaging property and spreading disease.
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 animalsincluding 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
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.
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.