Egg hatchings in Western Australia are expected to accelerate in early October. The plague locust is the most recurring and potentially damaging of the three. Locust outbreaks occur from time to time across Australia depending on climatic factors. Outbreaks of plague locusts often originate in semi-arid and arid zones of Australia. During Summer 1999-2000 and Autumn 2000 these areas received exceptional rainfall that allowed locust levels to build up to plague proportions and provided ideal conditions for the laying of the eggs, despite control measures.
Hatchings begin when moisture and temperature conditions are right in the Spring.
It takes from 4 to 6 weeks for locust nymphs to reach fledging stage and another 2 weeks to adult maturation enabling migratory flight. The main danger to agriculture occurs where crops are still green. Crop damage from bands of nymphs and migratory locusts can be significant. Even crops approaching ripeness can be attacked, particularly in the small green area below the grain head just prior to the readiness for harvesting. During daytime, plague locusts may feed and migrate up to a distance of 10-20 kilometres.