Key Information

National Status: Rare Regional Status: Rare Habitat: Fenn carr woodland

Status Overview

This is the Tanyptera region’s only Nationally Rare caddisfly. [Nationally Rare species are known from 15 or fewer post 31.12.1979 hectads; for A. brevipennis the count is 11].

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

  • First records were in 1862 from Hale Moss, Altrincham and an off-shoot at Bowdon after 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.

Life History

Larvae grow from late winter through spring and emerge as adults before the water-body dries up. They have not been found in autumn when their habitat is dominated by another dead leaf eating caddis, the very common Glyphotaelius pellucidus which finishes feeding as A brevipennis starts growing. It is probable that A. brevipennis hatches from the egg in autumn but stays small.

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.

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.