Species Account

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Summary Data

Season (Adult / Immature):

National Status: Common

Local Status: Very common and widespread resident.

Local Record: Grade 1   See here for explanation

Flight time: Two generations, May-Jun and Jul-Aug.

Forewing: 16-20mm.

Foodplant: Herbaceous and woody plants.

IMPORTANT - Please note that the maps and accounts are provisional, subject to change and further update.  The whole dataset still needs to go through the final verification process and it is likely that a very small number of records will not satisfy the present requirements and there are other records that have not been formally submitted.  The information is for guidance only.

Record breakdown:

Year first recorded190519831905
Year last recorded201120112011
Number of records23011664934
Number of individuals35852027574
Unique positions25918554
Unique locations19316418
Adult records21021614526
Immature records6012

For the region, we have a total of 4934 records from 418 sites. Earliest record on file is in 1905.


2289 Knot Grass 02 Larva
© Clive Pinder
2289 Knot Grass 01
© Tom Morris

Species Account

For further information refer UK Moths.

Davey, P., 2009: A widespread species in Britain, the larva is polyphagous. In Dorset, the moth is ubiquitous and at low density, occasionally rising to frequent, particularly in sallow-rich localities. Two brood cycles seem to be established, with a double brood emerging by mid-April and again from mid-July; a single brood emerges from early-June. Warm summers occasionally spawn an additional partial generation from either brood cycle, as evidenced by the following light trap records: West Bexington, on 1 October 1997, 8 November 2004 (R Eden), Puddletown, on 17 October 2003 (H Wood Homer), Iwerne Minster, on 4 October 1959 (H Moore), Shapwick, on 13 October 2003, Gaunts Common, on 11 October 1995, 8 November 1995 (P Davey), Arne, on 9 October 1992, 30 September 1995 (B Pickess), St Ives, on 3 October 1988 (Dr J Clarke).

See background to species accounts.  Index of Vernacular names - Search - Random Species