I'm Steve Ember with the VOA Special English Agriculture
Report.
There are lots of insects that farmers hate. But there also are some they
like. These protect crops against damage from other insects. A good example is
the lady beetle, also known as the ladybug.
Lady beetles are a natural control for aphids.
Aphids are tiny insects that develop colonies on plants and eat plant fluids.
Aphids can also spread crop diseases. Adult lady beetles can eat fifty aphids a
day. The young beetle larvae can eat hundreds of aphids.
Lady beetles are
red, orange or black. They often have black spots, though some have light
colored spots. Different kinds of lady beetles have different numbers of spots.
There are lady beetles with four, five, seven and fourteen spots.
Many of the well-known kinds of lady beetles come from Asia or Europe. They
now are common throughout the United States.
American scientists imported one kind of lady beetle, the multicolored Asian
lady beetle, as early as 1916. They released them as an attempt to control some
kinds of inspects. Over the years, the beetle has become established, possibly
helped by some that arrived with imported plants on ships.
Experts say over 450 kinds of lady beetles are found in North America.
Some are native to the area. Others have been brought from other places. Almost
all are helpful to farmers.
The Asian lady beetles now in the United States probably came from Japan. The
Asian lady beetle eats aphids that damage crops like soybeans, fruits and
berries.
In the southern United States, Asian lady beetles have reduced the need for
farmers to use pest-killing poisons on pecan trees.
This popular tree nut suffers from aphids and other pests that the beetles eat.
But some people say the Asian lady beetle has itself become a pest. Lady
beetles have no food after crops have been harvested. It is time for them to
prepare for winter. Normally this is in the ground, but it can also be in
someone’s home. Some farmers also worry that the beetles may eat their
late-autumn fruit crops.
Experts say Asian lady beetles may appear in large numbers in some years. But
they say the insects are too helpful to consider pests.
This VOA Special English Agriculture Report was written by Mario Ritter. Read
and listen to our reports at voaspecialenglish.com. I'm Steve
Ember.
ladybug : 瓢蟲(chóng)
aphid : 蚜蟲(chóng)
pecan
tree : 美洲山核桃樹(shù)
