Copper-bellied Ant Ochetellus glaber

Don't let the microscopic size fool you. At just 2–3 millimeters, this is among the smallest ant species, yet it's become one of the world's most successful invasive species. Starting from Australia, it's now established in China, Japan, India, the Philippines, Hawaii, Florida, and numerous Pacific island nations. Males are even tinier at just 1.6 mm. Despite its diminutive size, this tiny invader seriously threatens native ant communities, outcompeting local species through sheer competitive aggression wherever it spreads.