The typical male midge antenna has about a dozen short segments followed by one very long segment. The ratio of the long segment length to sum of the ones before it is the "antenna ratio."

On this antenna the short segments end around where the feathery part starts. You can see the rings separating the short segments.

Females usually have about half as many segments as males. The major exceptions are subfamily Tanypodinae, where both sexes usually have 11-15 segmented antennae, and species of Orthocladiinae that mate on the ground, where both sexes usually have 5-7 segmented antennae.