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Locusts as pests
Locusts can inflict widespread and severe damage to pastures, cereal crops and forage crops. In closely settled areas they may also cause considerable damage to vegetable and orchard crops.
Losses may amount to several millions of dollars unless effective control action is taken. In 1984 during a major outbreak of the Australian plague locust, estimated crop loss was $5 million. A cost-benefit analysis estimated that without locust control over $100 million of crop losses may have occurred.More recently an economic analysis of APLC locust control during 1999-2004 concluded there is a cost benefit ratio of approximately 1:8.
Dense aggregations of locust nymphs (hoppers) are called bands. Damage by bands is usually confined to pasture although crops, particularly young winter cereals, are very susceptible.
Bands may extend over several kilometres and are often visible from the air.
An aggregation of adult locusts is called a swarm. A swarm may consist of millions of locusts and can cover an area of several square kilometres.
Adults of the Australian plague locust and spur-throated locust are capable of migrating over very large distances within a 24 hour period. Migrations up to several hundred kilometres overnight are not uncommon and this behaviour can lead to the sudden appearance of large numbers of locusts in areas previously uninfested.
A large swarm of adult locusts can consume several tonnes of plant material every day, quickly devastating any crops or pastures in their path.
For further details on the economic importance of each locust species refer to the separate web pages on the Australian plague locust, spur-throated locust and migratory locust.
Also see...
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About the Australian plague locust for more information on what factors control the migration of this species.