What sort of caterpillar is this??

[Kathleen Moon]

CB wrote:
> 
> My wife was collecting some foliage for a floral display for a wedding
> and noticed a caterpillar she had never seen before on an oak leaf.
> 
> About 3 cm long, light green, hairy with four lighter coloured tufts
> about half way down its back. A reddish-brown horn at one end (not sure
> if head or tail). Seems not to move much in the day, but assume busy
> during the night since oak leaf is eaten and copious droppings (approx 1
> mm spherical). If the leaf it sits on is disturbed the creature moves a
> bit and dark brown stripes can be seen in the concertina folds of its
> segments.
> 
> We can't find anything which looks or sounds like this in the books.
> Does anyone know what it might be??
> 
> Habitat: Oak trees close to a fast flowing river in a relatively
> unpolluted rural location in South Wales. Local rock is Millstone Grit
> or something similar (between Carboniferous Limestone & Coal Measures).
> Altitude approx 200m. Weather wet, temperature range: day 18C night 7C.
> 
> Thanks in anticipation of any enlightening suggestions ....

You are in Wales?  Contact Neil Jones <Neil at NWJONES.DEMON.CO.UK>.  He
will know what it is.  He is an entomologist involved in entomological
conservation efforts and lives in Wales - speaks the language and sings
it, too.