Three species have laid their eggs: the Australian plague locust (Chortoicetes terminifera), the migratory locust (Locusta migratoria), and the spur-throated locust (Austracris guttulosa). But it is the Australian plague locust that has laid its eggs most widely.
Females can lay 30 to 60 eggs per cycle up to four times in their short lives. Eggs laid in the Southern Hemisphere autumn about the same time as spring in Earth's Northern Hemisphere could survive in the ground until January (mid-summer in Australia) if there is not enough rain for them to hatch, Macdonald explained.
"Under ideal conditions, locusts can hatch, mature, mate, and lay eggs within six to eight weeks, meaning there could be as many as four generations born before next winter," he said.
Even at the nymph stage, when they are unable to fly, bands of locusts can crawl up to four-tenths of a mile (one kilometer) from their egg beds and consume all vegetation in their path.
Locusts can be sprayed with insecticides on the ground about two weeks after they hatch, when they are still flightless and starting to form dense bands.
Once the insects can fly, however, swarms can travel more than 300 miles (500 kilometers) a day in search of food and must be sprayed from the air.
Although 264,000 acres (107,000 hectares) of land have already been sprayed, the first swarms caused an estimated 24 million U.S. dollars in damage and laid billions of eggs.
Farmer Angst
The main farmers' representative group, the NSW Farmers' Association, expressed concern that not enough of the required insecticides have been ordered to cope with the outbreak.
"While the government has twice as much chemicals on hand as [it had during the egg-laying period in March and April], this may not be enough if all the egg beds hatch," association president Mal Peters said.
"We have been assured that there is enough chemicals. But some areas may need to be sprayed three times, and the government must be ready to top up its supply if necessary."
The main insecticide, Fenitrothion, can kill locusts within 24 hours.
Farmers are better prepared this time, Peters said, but this may be of no use if enough chemicals are not made available.
"Locusts are best sprayed during the very early stages of their development, so we can't afford to waste any time," Peters said.
But Macdonald believes the government has prepared well, having already authorized the distribution of enough chemicals to treat 1.3 million acres (540,000 hectares).
"Response teams will also carry out aerial control when the size and density of bands are too large for landholders to treat on their own," Macdonald said.
Don't Miss a Discovery
Sign up our free Inside National Geographic newsletter. Every two weeks we'll send you our top news by e-mail. (See sample.)
|
SOURCES AND RELATED WEB SITES
|
