Complex sentence: In the 1930s, colonies were accidentally introduced into the United States through the seaport of Mobile, Alabama: cargo ships from Brazil docking at Mobile unloaded goods infested with the ants.
Split into simpler sentences: In the 1930s, colonies were accidentally introduced into the United States through the seaport of Mobile, Alabama. Cargo ships from Brazil docking at Mobile unloaded goods infested with the ants.