Essex Skipper butterflies closely resemble and are often found in company with Small Skippers.  Because of the similarities, the Essex Skipper has been overlooked both in terms of recording and ecological study, and it was the last British resident species to be described (in 1889).  The simplest means of distinguishing between the two species in the field is by examining the undersides of the tips of their club-shaped antennae; they are black in the Essex Skipper and orange or brown in the Small Skipper (place your mouse over the image to see the antennae underside).  However misidentifications still occur.  The distribution of the Essex Skipper in Britain has more than doubled in the last few decades.