New species in north America
Hundreds of different species of plants and animals have arrived in the united states.
This number has increased greatly as international travel and business have increased.
Some of these new “ residents” have caused problems for agriculture or for the environment.
The Mediterranean fruit fly, for example, arrived in California on some imported fruit in the 1970s.
In its original home in the Mediterranean area, it had never caused much damage.
In California, however, it multiplied very quickly.
Soon the California fruit industry was in trouble.
The government had to take serious measures, including using lots of chemicals to try to kill the flies.
However, they have not managed to get rid of the fly altogether.
Another example of an animal that has recently settled in north America is the zebra mussel.
This small shellfish was first discovered in the great lakes in 1986.
It may have come over from Russia on a cargo ship.
In a very few years zebra mussels had spread over all the great lakes and into many important rivers.
They have grown into thick masses, covering many areas of lakes or river bottoms.
They have also covered and closed up pipes for power stations and water treatment centers.
Government officials say that the mussels have caused many millions of dollars worth of damage.