阅读理解。
Insects Eating Your Crops?
Call on a Ladybug
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 (蚜虫). 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 are now 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 insects. 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. They 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 be considered pests.
1. What do ladybugs look like?
A. All kinds of ladybugs are of the same color.
B. Most of them are red,orange and black.
C. They each have the same number of spots on them.
D. The farms like them.
2. Asian ladybugs have been in the United States for___．
A. nine decades
B. hundreds of years
C. half a century
D. a century
3. Which of the following is NOT supported in the passage?
A. There are more than 450 kinds of ladybugs in North America,including native ones.
B. Only some imported ladybugs are helpful to the local plants.
C. Soybeans,fruits and berries are favorites of Aphids.
D. Pecan trees are common in the south of America.
4. According to the experts,ladybugs are _____ .
A. more helpful than considered as pests.
B. more pests than helpful insects.
C. helpful as well as destructive.
D. are more destructive than helpful.