What do you usually do when a flying insect lands on your arm? You may blow it away．But what if that insect is a ladybug（瓢虫）? It is possible that you would let it stay．What is it about ladybugs that we like?
Farmers once thought ladybugs were a good lucky sign．A ladybug in the field meant the crops would be successful and that the weather would be good．The farmers may have thought too highly of such a small bug，but in fact ladybugs do help out with the crops．They eat harmful insects．
Actually，it is not the adult ladybug that eats other insects． It's the baby ladybug．When the baby ladybugs hatch（孵化），they are very hungry and will eat mites，aphids，mealy bugs，green flies，and other crop-destroyers． In the 1800s，ladybugs were brought all the way from Australia to California and set free among orange trees that were dying from being eaten by insects．They completely saved all the trees．
Ladybugs go about their daily business without worrying much about anything．Very few birds or insects will eat a ladybug because it gives off a dangerous fluid（液体）．Ladybugs also protect themselves by playing dead．They fall off leaves and never move until their attacker goes away．
So the next time you see a ladybug，think about what it may be doing．Maybe it is off to save an orange tree．Maybe its next move will be to roll off a leaf and play dead or stand up to a bird about 100 times its size．Maybe it's letting you know that the weather will be good tomorrow．Who knows? Ladybugs are special that way．
Ladybugs were brought from Australia to California in the 1800s to____．

A．add more ladybugs to area

B．report the weather for farmers

C．act as a lucky sign of good crops

D．save orange trees by eating insects

From the passage we know that ____．

A．it's the adult ladybug that eats most o{ the harmful insects

B．ladybugs often roll off a leaf and play dead to attack the birds

C．ladybugs can give off a dangerous fluid to protect themselves

D．the baby ladybug mainly eats mites，aphids，mealy bugs，and oranges

The underlined phrase "stand up to" most probably means ____．

A．watch	B．support
C．save	D．fight