Dear David
You ask a good question about Dolichovespula media - at the time the Essex Red Data List was first put together, this wasp was still rare in the county with only very few records. Although it had been spreading in southern England for some years it was considered to still warrant Essex listing (and indeed is still officially Nationally Scarce (Notable A). I have now removed it from the ERD List to reflect its present distribution and status in the county.