Native habitat: South America
Death toll: About a dozen Americans die from being stung by a fire ant yearly.
Why you should be terrified of them: About 5 million Americans are stung by fire ants every year. The fire ant attacks with both a bite and a sting.

The venom that is injected by these fire ants is known as histamine. Histamine is a chemical that produces pain, itching, swelling and redness of the skin. The pain of a fire ant sting is more bearable than a bee or wasp sting. These stings form into a white pustule within a day. An allergic reaction may occur resulting in sweating, slurred speech, chest pain, shortness of breath, and shock, among other symptoms. The sting itself is usually not life-threatening, but secondary infections can result in death.