An Up and Down Day

Wednesday 3rd June 2026, Coed Cwmgolog and Siercwm, Ceri Forest

Managed by Natural Resources Wales, this large, publicly owned woodland is notable for its rides being frequented by Wood White butterflies. To quote directly from the NRW Resources Plan 2026: The tree species composition is largely coniferous, with elements of broadleaves in areas which have been felled and replanted. The total plan area is 1009 hectares. Large parts of Ceri forest are on steep ground in a very exposed position and are susceptible to severe damage in storms. This makes management more challenging and has resulted in some large clearfells to clear up storm damage.

This was another day in which the weather could fairly be described as “changeable”. Though given the miserable conditions upon arrival, we were glad of the later changes!

photo: John Lyden

Waterproofs were donned, concerns about a lack of sufficient layers of clothing were aired and eventually the shelter of the cars was slowly and reluctantly left behind. Our route was downhill, we hoped in altitude only.

One of the first finds was an organism we had seen a few weeks previously in Brineddin Wood, not a million miles away in southwest Shropshire: Phytobia carbonaria, a fly who’s larvae mine the stems of hawthorns and apples. Cutting a hawthorn stem revealed the tell-tale markings in the wood.

Another of the broadleaved tree species in this conifer-dominated landscape is Rowan, present along much of the route we followed. Its unripe berries are home to the larvae of a micro moth, Argyresthia conjugella, which goes by the name of Apple Fruit Moth due to it similarly targeting developing apples. This is the moth:

Around this time a slug was spotted, probably enjoying the weather rather more than we were. The identification is inconclusive but it seems to be good candidate for the Durham Slug, Arion flagellus, also rather excitingly/alarmingly known as the Spanish Stealth Slug!

photo: Keith Fowler

We continued downwards, aiming at the lower rides where Wood Whites had been seen in numbers only recently. Though they would be moribund in the prevailing weather, we hoped they would be found roosting in the vegetation. Reaching the bottom, we continued along the left-hand path at an intersection. But no such luck with the Wood Whites. Fortunately our luck with the weather was rather better. A miraculous parting of the clouds occurred and shortly afterwards the scene looked like this:

Surely this must bring out the Wood Whites? But no. We did come across a cluster of Common Blues though, initially roosting in the grass….

…and then up and about once the sunshine had warmed them up sufficiently. It also brought out our first Large Skippers of the year.

And a few Garden Chafers.

 

Reaching the farthest point of our explorations we turned and retraced our steps to where we had left some members of the party behind. In so doing we disturbed a couple of Common Green Grasshopper nymphs.

And so back to our sole vacuumer for the day, still diligently suction-sampling the verges near the bottom of the original descent. 

Here we pitched camp for lunch. The sun continued to shine and we continued to dry out. When lunch was consumed and packed away a further exploration of the valley bottom was made and behold! A Wood White flew past, paused long enough to show that it was unquestionably a Wood White, and was gone again. And that was that! No photographic evidence was possible I’m afraid.

Some of the finds in this area included Euura bridgmanii galls on Sallow

photo: John Lyden

A March Moth caterpillar on Sycamore

And a Dock Bug on… dock.

We began a slow ascent back to our starting point, with the aim of then continuing onwards in another direction. A Common Groundhopper was spotted at the edge of the track

A flea-weevil, Tachyerges salicis (they really can jump!) was tapped from a Sallow.

And a Hairy Shieldbug was spotted at ground level. 

Finds from the vacuum have largely gone under the radar in this report. One nice find was the 2mm micro ladybird Nephus redtenbacheri (the Red-patched Ladybird). This rather odd photo is framed by two fingers holding the glass tube in which it is temporarily residing.

By now the weather was starting to look threatening again. Brief (for the moment) squalls passed through. The now wet again Sallow foliage revealed a pair of Puss Moth eggs.

photo: John Lyden

And then, just as the heavens opened in a particularly meaningful way, an Eyed Hawkmoth was spotted sitting in the grass at the side of the track. What a super sight in the now dismal again light.

Delayed by the hawkmoth and now sopping once more, we trudged onwards and upwards, our leading member, who had unfortunately missed the moth, capturing our ascent.

photo: Clare Boyes

Near the top, and now with only the cars and dryness as aims, we had our third encounter in as many weeks with a Golden-bloomed Grey Longhorn beetle.

While the downturn in the weather was not dampening the spirits of a pair of Common Blues.

We made it back to the cars and departed, steaming slightly. A final couple of images will serve to sum the day up. Firstly, here is the same view, taken on arrival and then later when the weather was in one of its more benign moments.

photos: Keith Fowler

And lastly, this is the view which greeted one of our party as he walked home.

photo: John Lyden

This is a site which clearly has much to offer. I’m glad that we were able to appreciate it in the sun for at least part of the day. Many thanks to NRW for allowing us to visit and to do what we do.

  
 
Photographs © the author except as noted.