Distribution of the Australian plague locust
The Australian plague locust is widespread on the mainland and is commonly found in a variety of grassland and open, wooded habitats.
Adult Australian plague locusts are nomadic and swarms can move twenty kilometres in a day. They also make long distance nocturnal migratory flights at heights up to 1000 m. They can be transported over long distances by upper-level winds and are therefore occasionally found in more coastal parts of the mainland and even in northern Tasmania. In eastern Australia migrant locusts sometimes establish populations in valleys east of the Great Dividing Range, such as the Hunter Valley, but these populations usually die out after several generations.
The Australian plague locust is inactive at temperatures below about 15o C and most adults die during the winter months in the southern part of its distribution area. Most eggs laid in autumn in southern areas enter diapause and only resume development in late winter when cold temperatures continue to delay hatching until spring. Therefore at the start of spring the majority of the population occurs as eggs in the soil which hatch later in spring. The lifecycle of this species gives rise to several generations each year. There are typically three generations corresponding roughly to the spring, summer and autumn seasons, but there may sometimes be two or four depending on latitude and regional conditions.
Within the geographical range of the species in eastern Australia certain regions are subject to frequent locust infestations. Parts of these regions provide favourable habitat for locusts in different seasons. The map below shows the frequency of infestation, estimated by the number of generations during the last 30 years in which high density nymphs or adults have been recorded in 0.5 degree grid cells. During an outbreak high density locusts may occupy an area for several generations. The shading represents the infestation frequency - from white areas with no recorded infestations, through to blue - where high density locusts were recorded in 30 generations. The total numer of generations recorded sprarately during 1977-2008 is 95. Parts of the Riverina, Central West and Far Western NSW, and parts of Southwest Queensland have the highest recorded frequency of infestation. The source of the information is APLC survey and control records.
Frequency of locust infestation in eastern Australia from 1977 to 2008
The shading represents the infestation frequency - white areas with no recorded infestations,
through to blue - where high density locusts were recorded in 30 generations.
10 Nov 2009