What Is the Smallest Butterfly in the World?

The smallest butterfly in the world is the Western Pygmy Blue, which has an average wingspan as an adult between 2/5 and 3/4 of an inch with females' wingspans generally slightly larger. Western Pygmy butterflies live in the United States and are found in Texas, California, Idaho, Nebraska and Oklahoma, and even living as far south as South America. These butterflies bear little difference between genders, except for size, and have distinct coloration on their coats to distinguish them from other species.

Western Pygmy butterflies have copper-tinted wings that turn a blue color at the base. Their underwings also turn a golden-brown color near the tips, but transform to a gray hue near the base. Females and males bear the same colors and patterns, although females may grow to twice the size of males.

Western Pygmy butterflies, like many species, migrate southward to escape the coldest days of winter. They prefer a habitat of lowland areas, such as arid deserts and plains. These butterflies feed on the flowers and fruits of plants in the goosefoot family. Availability of food supplies directly affects population size, and the disappearance of the plants in the fall can lead to a sudden population decline. Western Pygmies go through four stages of life, like other moths and butterflies, starting as caterpillars and eventually becoming butterflies.