The plague of locusts that hit Hohhot last week had trickled
down to only a handful yesterday, said agricultural officials in
the capital of north China's Inner
Mongolia Autonomous Region.
The brown insects, whose scientific name is Oedaleus asiaticus,
have been puzzling technicians, as many experts had previously
believed that this type of locust could not migrate a long
distance.
Chen Jing, director of the city's plant protection station,
said: "The number of locusts peaked on Wednesday and Thursday in
downtown, as they reached up to 200 per square meter in some
areas."
The insects covered trees, walls and windows in some quarters of
the city, gnawing at leaves, grass and anything they could eat, she
said. The problem was especially acute in brightly lit areas
because the locusts are photokinetic -- they move in response to
light.
But the creatures seem not to have caused any substantial damage
to the city, Chen said.
"They have either died or flown away and, by today, there were
only sporadic plagues of locusts in the city center," she said.
Some local people claimed that the insects were attracted by
Hohhot's strong night-time lights and flew to the city from nearby
prairies, but Chen said she personally doubted this theory.
"It is common knowledge that this type of locust is unable to
travel long distances," she said. "Besides, the prairies and
farmland nearby did not have such massive numbers of locusts
recently as, in many areas, the density was four to 20 locusts per
square meter.”
Zhang Zuoran, of the Inner Mongolia Autonomous Region Grassland
Plant Protection Station, said the unprecedented numbers of locusts
in Hohhot may prompt a revision of people's traditional views of
the insect.
"Many people have taken it for granted that these locusts could
not migrate for long distances," he said. "But our on-the-spot
investigation indicated they can fly a fairly long distance if
powered by the wind." Usually, this type of brown locust can fly
only up to 120 meters away from its normal habitat, Zhang said
But, on July 19, Zhang and his colleagues observed in a
grassland area of Shiziwang League -- 100 kilometers north of
Hohhot -- that the relatively strong winds had enabled the locusts
to travel much longer distances.
(China Daily August 5, 2003)