One of the most local and hard to connect with hoverflies is Eristalis cryptarum, the bog hoverfly.  Never present in huge numbers at any of its remaining sites, it is also quite flighty and can easily put up.  

At least it is fairly easy to recognise - in the field the impression is more dumpy and gingery than your average eristalis, and (unless its on marsh marigold) the all yellow legs stand out.

So when the Devon Fly Group organised an extended twitch across some of its known sites it was a good opportunity to catch up with this very localised species, and despite the poor weather a male was found by Andrew Cunningham and Rob Wolton at Challacombe.

One great mystery about this species - the larvae have never been found !

The entry in Stubbs explains the rapid decline of this species, its apparent loss, and rediscovery in 93 by Roger Morris and Stuart Ball. Needless to say this is an endangered species, and being readily field identifiable (given good views) there is no justification for collection, however we could certainly do with more records - and any obvservations of ovipositting females would fill a huge gap in its known ecology!

Previous range includes Cornwall to the New Forest and it is easily overlooked...