Crop circles in Wyre!

Ian Wallace writes: “While looking for caddis larvae in Wyre on the 8th April this year I noticed several small bulls-eye circles, about a centimetre across, cut through the fine silt layer on the top of a submerged stone at the mouth of the Park Stream (SO 7547 7661).  After a bit of thought I realised I must be looking at the marks left by one of Wyre’s commonest caddis, Agapetus fuscipes. The larva has flat ended mandibles that scrape over the rock surface to detach diatoms, algae and organic silt which they swallow as food. One of the greatest problems for the larva is to avoid being swept away by the current, so they always have one end of the case anchored to the rock by a few silken threads. That enables them to pivot round the anchor point, the bulls eye of the marks, as they feed. They might only work part of the circle. After clearing an area they will then attach the free end of the case before detaching the original anchor so they can swing round to make a little forward progression. There has to be just the right combination of silt depth and current speed and density of individuals for these mysterious circles to appear, made by little Agapetus as it harvests its crop of diatoms.”

Agapetus fuscipes feeding marks, Park Brook, 8 April 2016 ©Rosemary Winnall

Agapetus fuscipes feeding marks, Park Brook, 8 April 2016 ©Rosemary Winnall

Live Agapetes fuscipes showing evidence of grazing, Park Brook, 4 May 2016 ©Rosemary Winnall

Agapetus fuscipes, Wyre Forest, 21 April 2016 ©Rosemary Winnall

Agapetus fuscipes outside case, Wyre Forest, 21 April 2016 ©Rosemary Winnall

 

Rare Tinodes caddisfly larvae

We were pleased to meet up with Ian Wallace in Wyre this April and to obtain permission for him to visit a few stream sites on private land around the forest so that he could check for the presence of some rare caddisflies. Ian was very pleased to find both Tinodes pallidulus and Tinodes rostocki, both nationally rare species, in Bavaney Brook above Furnace Mill.

Ian Wallace in Bavaney Brook pleased to have found 2 species of Tinodes, 8 April 2016

Tinodes pallidulus galleries, Bavaney Brook, 8 April 2016

Porcellio dilatatus a woodlouse

This woodlouse Porcellio dilatatus is not often seen and is probably overlooked. It was found in a dungheap on a farm at Callow Hill and this appears to be the first record for Worcestershire. Compared with other woodlice, this species is wider in relation to its length, and grows up to 15mm. One distinguishing feature is the distinctive shape of its rear telson or ‘tail’. Although there are only scattered records across the UK, it has been recorded around buildings, farmyards, and in dungheaps.

Porcellio dilatatus, Callow Hill, 31 October 2015, ©Rosemary Winnall

Porcellionides pruinosus

Hundreds of these woodlice were found on a large active manure heap in Callow Hill. This is their specialist habitat and their numbers can expand quickly in suitable conditions. There are not many records from Worcestershire, so one to look out for. The adults have a distinct glaucous bloom when found and white legs, and run very fast when disturbed.

Porcellionides pruinosus, Callow Hill, 2 September 2015 © Rosemary Winnall

Caddis Tinodes pallidulus McLachlan

Ian Wallace, UK Caddis Recording Scheme Organiser, has contributed information about the the caddis Tinodes pallidulus McLachlan, found commonly in the Wyre Forest:

This national rarity has Wyre as one of its four extant known sites. On June 3rd, I was pleasantly surprised to find this insect common along the Dowles Brook from Park House to Forest Lodge and a little way up both Forest Lodge and Kingswood streams.  Larvae of this genus make characteristic galleries in which they graze algae from the surface of the stones but may also make the galleries above the water level but wet from the surface film.  These latter type are like grow tunnels pushed up into as much light as possible so algae grow on their inner walls on which the larva feed.  The species has an annual life cycle and the galleries are easiest to see now.  Look for them on stones at the edge of the stream where the water flow is moderate to fast.  Note if you see similar galleries elsewhere it is not necessarily T. pallidulus .  The larvae I found key out as pallidulus but I hope to rear some to adult just to make sure!

Tinodes pallidulus larval cases, Wyre Forest, 3 June 2015 ©Ian Wallace

Tinodes pallidulus larval cases, Wyre Forest, 3 June 2015 ©Ian Wallace

Bristly Millipede Polyxenus lagurus

Gary Farmer found this beautiful little Bristly Millipede in Wyre near Lodgehill this week. It only measures 2-3mm so is not easy to spot. We have been looking for it since Katy Dainton found one at the Great Bog in February. They are nocturnal and feed on lichen and algae and are found on old walls, trees and stumps. Apparently they are most easily found by searching walls at night with a torch. Wyre Forest is right on the edge of its range.

Bristly Millipede Polydexnus lagurus, Town Coppice ©Gary Farmer