Status Overview

This is the Tanyptera region’s only Nationally Rare caddisfly, known from just 11 hectads since 1980 (the limit for a status of Nationally Rare is 15).

The recent review of the conservation status of UK caddisflies gave this species the grade of “vulnerable” due to the small area it occupied. Recent loss of habitat was not then detected, but it may have been lost from one site (not in this region) in the past couple of years.

Regional sites

VC58

• Hale Moss, Altrincham (and an off-shoot at Bowdon): First records were in 1862 only a year after its addition to the UK list, made by Benjamin Cooke. The last records from this site was 1868.
• Wybunbury Moss – first record 1954 but not seen here since 1998 until re-found by Ian and Brenda Wallace in 2018 following a Tanyptera project supported search.
• Hatchmere Fen – first record 1982 but not seen here since 1984 until re-found by Ian and Brenda Wallace in 2018 following a Tanyptera project supported search.
• Danes Moss – 1991 – not re-found despite a search by Ian and Brenda Wallace in 2018.

VC60

• Hawes Water, Silverdale: 1964

Habitat

The larvae are found in shallow pools, in fen carr woodland. The pools have a bottom of dead leaf fragments and a slight water flow. They dry up over summer. The secretive adults hide amongst dense vegetation and wood debris at the breeding site.

A view of Wybunbury Moss pools showing collapsing trees, and mosses overgrowing their roots, photographed on 14/1/2019. [Image: Ian Wallace]

An egg mass was found under this moss on 3/10/2018 (see below) which, at the time, was many centimetres above the water. This photograph taken on 14/1/2019 shows that the location had been inundated by rising water. [Image: Ian Wallace]

Life History

Larvae grow from late winter through spring and emerge as adults before the water-body dries up.

The adult is presumed to hide away over summer and the female will not develop eggs until late summer, laying in September under woody debris in the still dry, but damp, pool bottoms.

Conservation Issues

The pools where it lives eventually dry-up by natural succession, but under natural conditions new carr develops, ages and becomes suitable. However there may be no new habitat developing at some sites. Long-term drying out of sites, or droughts can dry up the pools prematurely. This may have caused A. brevipennis to be lost from Wem Moss in Shropshire. Wetting the habitat by damming is also unfavourable as they need water flow and pools that actually dry up. Removal of a lot of the tree cover at a site would probably result in local extinction.

Recording

The adult does light trap but only at its site and the insect resembles several other common species.

The larval case, triangular in section and made of dead leaves is characteristic. It also persists after the adult has emerged and when the pools dry up. The latter is very useful as the habitat is often dangerous to access when wet.

Circular larval damage on a dead oak leaf with cased larva in centre. Cut-outs are used to build larval case [Image: Ian Wallace]

The open end of a larval case. The sides slightly over-hang the bottom. [Image: Ian Wallace]

A larva and cut leaf as found in situ in a pool at Wybunbury Moss [Image: Ian Wallace]

Egg mass at about 6 weeks old after laying. Some hatched larvae are visible within the jelly [Image: Ian Wallace]

A strong torch can be used to find small larvae of Anabolia brevipennis. [Image: Ian Wallace]

Future work in the region

Wooded mossland sites and dense carr of lakes fens are potential sites and the initially unattractive pools of such habitats are worth investigating. Wooded mossland sites are potentially under greatest threat as they are often regarded as degraded and candidates for serious tree clearance. A preliminary survey and retention of some suitable habitat is desirable. Its status at three regional sites has been checked in 2018; Wynbunbury Moss, Hatchmere fen and Danes Moss (searches of the first two were supported by the Tanyptera Project small grants scheme – see report). Wynbunbury Moss had a large population and has many other rare species whose status is monitored, perhaps A. brevipennis could be added to the schedules for the site.

Further Information

Studies on the rare caddisfly Anabolia brevipennis (Curtis) in Cheshire, in 2018 and 2019

Barnard, Peter and Ross, Emma (2012) The Adult Trichoptera (Caddisflies) of Britain and Ireland. Handbooks for the Identification of British Insects, 17 (1). Royal Entomological Society, St Albans [IDENTIFICATION REFERENCE]

Wallace, I.D., Wallace, B. & Philipson, G.N. (2003) Keys to the Case-bearing caddis larvae of Britain and Ireland. Scientific Publication 61 of the Freshwater Biological Association. [IDENTIFICATION REFERENCE]