RALEIGH, N.C. — Wake County is getting some unwelcome new residents -- fire ants.

The ants originally came into the United States from Brazil in the 1920s, but they have only recently invaded the Triangle area.

The fire ants make large mounds in the dirt. When those mounds are disturbed, thousands of fire ants pour out at once and attack. They can bite and sting, causing painful red welts.

Experts said the best way to fight them is to put out commercial baits in the spring and fall. You should also apply a licensed pesticide in the summer.

Meanwhile, state and federal government researchers are working to find natural enemies, such as phorid flies, that attacks the ants and paralyze them. Researchers hope the fly will at least slow the spread of the aggressive ants.