Red fire ants are native to South America. They entered and spread across the United States in the 1930s. They build large nests in the form of dirt mounds and live in colonies. If bitten by a red fire ant, an extremely painful and itchy blister appears that may become infected if scratched and broken. Red fire ants attack a large variety of organisms if threatened or provoked.
Which solution would be most effective in controlling the spread of these ants in the United States?
Physically break the ant mounds.
Spray weed killer around the ant mounds.
Kill individual ants when noticed.
Add biological control organisms to the ant mounds.