This is the VOA Special English Agriculture Report.

Farmers in parts of the United States have struggled for years with an invasion of red imported fire ants from Brazil. These insects do major damage, unlike native kinds of fire ants.

Each year they cause an estimated six billion dollars worth of damage in the United States. More than one billion dollars of that is just in Texas.

The ants are thought to have arrived in the southern state of Alabama in the nineteen twenties or thirties. Since then they have spread northward and all the way to the West Coast.

They ruin crops, damage soil and get into animal feed. They also damage electrical equipment and machinery. Not only that, they injure animals and workers. So farmers have to deal with medical costs and lost labor.

Fire ants get their name because when they sting, they inject poison into the skin that causes a feeling of intense burning. Some people suffer life-threatening reactions.

Colonies of red imported fire ants can be found in cities as well as farming areas. They can go deep underground to survive periods of little or no rain. They have no native predators, no creatures that like to feed on them.

But one solution could come from the ants themselves, in the form of a virus that some of them carry. This virus may someday help control the population.

Scientists at the United States Department of Agriculture began to work with the virus about five years ago. The researchers observed one hundred sixty-eight nests of imported fire ants in Florida. They found the virus in almost one-fourth of them.

The researchers found that the virus affected every part of fire-ant development, including the eggs. The affected colonies died in about three months.

Now, government researchers want to work with a private company to produce large amounts of the virus. It could then be used as a biological control.

Other natural ways to fight the fire ants are also possible. One is the South American phorid fly. It lays its eggs on fire ants. When the eggs break open, the young flies eat the brains of the ants. But researchers do not know how well the flies would do in North America.

As much as the ants are hated, they do have a few friends among growers of cotton and sugarcane. The ants feed on insects that attack those crops.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Steve Ember.