Heavy-bodied pit viper up to 2.5 m. Responsible for more snakebite deaths in Central America than any other species — "the ultimate pit viper".

Highly potent hemotoxin causes catastrophic tissue damage and bleeding. Without antivenom, mortality reaches 7–9%. Aggressive when cornered.

Lowland forests, plantations, banana fields from southern Mexico through Guatemala, Honduras, Nicaragua, Costa Rica, and Panama.

Active hunter at night; sometimes climbs into low vegetation. Females give birth to up to 80 venomous neonates.

Up to 1.8 m. Unlike most rattlesnakes, has potent neurotoxic venom (similar to mamba). Common in dry interior valleys of Central America.

Neurotoxin causes paralysis and respiratory failure — different symptoms than US rattlers. Antivenom essential within hours.

Dry tropical forests, savannas, and farmland of Mexico (Yucatán), Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica.

Nocturnal in hot weather. Often found near villages and in agricultural areas. Causes most snakebite deaths in Costa Rican Pacific lowlands.

Brightly banded red-yellow-black snake up to 1.2 m. Related to cobras and mambas — the only elapid in eastern North America. "Red touch yellow, kill a fellow."

Powerful neurotoxin can cause respiratory paralysis. Bites rare — only ~25 per year in US — but require antivenom (which is increasingly scarce).

Pine flatwoods, scrub oak, leaf litter of Florida, Georgia, Alabama, Mississippi, Louisiana, parts of Texas and northern Mexico.

Secretive and reluctant to bite — must chew to inject venom. Often confused with non-venomous milk snake.

Dark brown bug 2 cm long with red-orange edges. Bites face at night (hence 'kissing') while you sleep. Transmits Chagas disease — a chronic illness affecting heart and digestive system.

About 300,000 people in US infected with Chagas (mostly immigrants). 30% develop fatal heart damage decades later. Vector range expanding north with climate change.

Wood-rat dens, log piles, dog kennels of southern US (Texas to Georgia), all of Mexico, Central America.

Active at night. Defecates near bite site — parasites enter through bite wound or rubbed-in feces.

'Killer bee' — hybrid of African and European honey bees, escaped Brazilian lab in 1957. Spread north and arrived in southern US in 1990; now in Texas, Arizona, Nevada, California, Florida.

Individual sting like normal bee, but they swarm aggressively — attacking in 100s for minor disturbance, pursuing victims 400 m. About 1–2 deaths per year in US.

Southern US (Texas, Arizona, California, Florida), all of Mexico, Guatemala, Honduras, Nicaragua, El Salvador, Costa Rica, Panama, Belize.

Easily provoked by vibration, sound, dark colors, exhalation. Stays angry for 24+ hours after disturbance.

Reddish-brown ant 2–6 mm. Invasive from South America since 1930s; now infests southern US from Texas to Virginia. Aggressive when nest disturbed.

Stings cause burning pustules. Allergic reactions can cause anaphylactic shock — about 80 deaths per year in US attributed to fire ants.

Open sunny areas — lawns, fields, roadsides — across southern US, Caribbean, parts of Mexico.

Builds large mound nests up to 60 cm tall. Step on a mound, hundreds swarm out and sting in unison.

Disc up to 1.5 m with whip-like tail bearing a serrated venomous spine. Common in Gulf of Mexico and Caribbean — popular with tourists at 'Stingray City'.

Stings only defensively when stepped on. Spine drives deep, often breaks off. Steve Irwin's death is a textbook example of chest impalement.

Sandy and muddy bottoms of Gulf of Mexico, Caribbean, southeastern US Atlantic coast.

Buries in sand. The 'stingray shuffle' (sliding feet) prevents most stings. Eats clams, shrimp.