Fireflies can reach up to one inch (2.5 centimeters) in length.

What is the average size of a firefly?

Most fireflies are nocturnal, although some species are diurnal. They are soft-bodied beetles that range from 5 to 25 mm (up to 1 inch) in length. The flattened, dark brown or black body is often marked with orange or yellow.

How long is a firefly in millimeters?

They range in size from 1/5 to 1 inch (5 to 25 millimeters). Fireflies found in the United States are about 1/2 inch (13 millimeters) or less in length.