The Essex skipper is very, very similar to the small skipper in appearance, habitat and larvae food plant and so it is quite possible that they are very underecorded and are more common than one might think. The main difference in appearance are the antennae; the Essex skipper as black tips that the small skipper does not have. A further clue to telling them apart is that whilst the small skipper is at its peak in June the Essex skipper is at its peak in July and in to August. Small skippers are still about during this time but it means that a 'small' skipper seen in July or August is worthy of closer inspection just in case.
There are just 10 reports of Essex Skipper in the database for 2017 and 2018 combined and these are mainly in July with just 2 in June and 2 in August. This reflects the pattern expected with the later emergence that the small skipper with reports of the Essex skipper from week 26 to week 31.
The 10 reports are all from different locations and half of these are coastal sites and the other 5 further inland but all are areas of rough grassland.
One would hope that more reports of Essex Skipper during the coming seasons might give us a better impression of the status of Essex skipper in Dorset.