– click for Adult Macro Verification Guidelines
– Rare / Uncommon / Scarce
– care required in the identification process, as confusion with similar species is likely – quality photographs required. Confusion Species: Grey Dagger
ID pointers: A grey to pale-grey moth, with long branched black basal streaks and black dagger like marks near trailing corner. Forewing can sometimes be tinged brownish or pink. See Grey Dagger
Distribution: (Last record: 1 September 2024 at Belper ) – Resident and widely distributed at a low density in lowland areas of Derbyshire. This species and Acronicta psi (Grey Dagger), are so similar that field ID cannot reliably be used. The only sure way is by appearance of the caterpillars. Dark Dagger caterpillar has a red dorsal stripe, whilst Grey Dagger caterpillar has a yellow dorsal stripe. If cannot perform a Gen. Det, then record as Grey/Dark Dagger agg.
*** Last updated on 2 October 2025 by RP ***
Forewing: 17-20mm
Last Recorded Year: 2024
Last Recorded By – Dave Evans
Last Recorded General Area – Belper
Selected Images: Melbourne – Tony Davison © – Dark/Grey Dagger agg
Image Gallery
No gallery images found for this moth.
Distribution Map for Acronicta tridens
Found 24 records
↳ 2 from After 2025
↳ 0 from 2020 - 2024
↳ 22 from Before 2020
↳ 2 from After 2025
↳ 0 from 2020 - 2024
↳ 22 from Before 2020
If the Map Layers function fails, just refresh the page and it should be OK after. Use the +- zoom on the top left, or on a tablet, use two fingers to zoom. Remember, the last layer you ticked is the one which displays the popup information - they sit on top of each other - de-select then re-select, to see the popup values.
Bedrock Geology ** indirectly affects moth distribution by influencing the type of habitat and food plants available in an area. In turn, this may affect the types of moths that can thrive, or where they can most likely be found.
NBN Atlas UK Distribution for – Acronicta tridens
⚠️ Please wait for the map to load fully – do not click the link shown.
Note – the NBN Atlas datasets are listed in the map below and vary in their currency (uptodateness) – however,
the map does give a general indication of the moth's distribution across the UK.
Monthly Records By Year:
Acronicta tridens
( data includes both Larvae and Adult Stages )
Monthly Counts By Year: Acronicta tridens
( data is based on 'Adult' stage records only. )
First/Last Recorded Dates: Acronicta tridens
Adult-only & Anything [Larvae, Pupae, Adult, Mines]
Shading shows moth presence between dates
Click the colour discs below to Select/De-select as Required
Recordings By Year: Acronicta tridens
( All data includes both Larvae and Adult Stages )
Annual Growth Rate (AGR): Acronicta tridens
AGR: 2.41% | Total % Change: 50%
CUSUM Analysis: Acronicta tridens
About this chart: CUSUM (Cumulative Sum) charts track long-term trends in moth populations [ filtered by 'Adult' and 'Mine' life stages ] by showing whether each year’s counts are above or below the historical average. Even small shifts build up over time, making trends of growth, stability, or decline easier to see. CUSUM highlights trend-consistency — asking: “Across the years, have moth counts mostly stayed above or below average?”
The data sample has 21 gap year/s here (zero records) between 2000 and 2025. The moth may have been present in those gap years, but no data was available. Too many year-gaps may exaggerate or skew the chart.
Counts for the current year (2025) are pro-rated based on data available up to month 8 (August) to provide a full-year equivalent.
ⓘ
Purple line rises = years better than average; falls = years worse than average.
Peak (best year)
Trough (worst year)
Growth periods
Decline periods
Population peaked around 2025, reaching above average levels. The lowest population point occurred near 2018, showing a significant decline.
What the Y-axis "Cumulative Deviation" means: Cumulative Deviation shows the running total of how each year’s moth population count differs from the long-term average. i
Hectad (10kmx10km) Coverage: Acronicta tridens
( data includes both Larvae and Adult Stages )
Flight Periods – Indicative –vs– Recorded Data
Acronicta tridens
Acronicta tridens
( data includes Adult Stage only )
Flight Period chart – the grey hatched area above, which can cross one or more months, pictorially represents the best guess we have for this moth's flight periods [month/s]. The coloured lines represent the actual months seen in flight, from site observation records received between 2020-2025.
Records Behind the Map and Charts - Acronicta tridens – 24 records available
Listed by Year - descending - scroll across to see all table columns
| Site Name | Tetrad | Date | Count | Stage | Source |
|---|---|---|---|---|---|
| Ingleby Ave, Derby | SK33L | 18/07/2025 | 2 | adult | vc57_irecords_extract |
| Markham Vale South Tip | SK47K | 17/07/2025 | 1 | adult | vc57_irecords_extract |
| Willington, Derby (site not precise) | SK22Z | 27/05/2018 | 1 | Adult | vc57_danes_bc_data |
| Main Street, Kings Newton | SK32Y | 15/10/2015 | 1 | Larva | vc57_irecords_extract |
| Brushfield Spar Quarry, Monsal Dale, Little Longstone | SK17Q | 17/05/2014 | 1 | Adult | vc57_danes_bc_data |
| Oaks Barn Cottage, Monyash Rd, Over Haddon, Bakewell | SK26D | 04/07/2011 | 1 | Adult | vc57_danes_bc_data |
| Oaks Barn Cottage, Monyash Rd, Over Haddon, Bakewell | SK26D | 23/04/2011 | 1 | Adult | vc57_danes_bc_data |
| Blacka Moor, Totley, Sheffield | SK28V | 05/09/2009 | 1 | Larvae | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 12/06/2008 | 1 | Adult | vc57_danes_bc_data |
| Wilmot St, Sawley, Long Eaton | SK43R | 01/08/1989 | 1 | Adult | vc57_danes_bc_data |
| Stanton Gate, Ilkeston (site not precise) | SK43Z | 17/07/1989 | 1 | Larvae | vc57_danes_bc_data |
| Lings Close,Ilkeston | SK44S | 27/08/1982 | 1 | Larvae | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 07/07/1932 | 1 | Adult | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 07/07/1932 | 1 | Adult | vc57_danes_bc_data |
| Willington, Derby (site not precise) | SK22Z | 27/05/1918 | 1 | Adult | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 12/06/1908 | 1 | Adult | vc57_danes_bc_data |
| Barrow on Trent, Derby (site not precise) | SK32P | 01/01/1885 | 1 | Adult | vc57_danes_bc_data |
| Barrow on Trent, Derby (site not precise) | SK32P | 01/01/1885 | 1 | Adult | vc57_danes_bc_data |
| Breadsall Moor, Derby (site not precise) | SK33U | 01/01/1883 | 1 | Adult | vc57_danes_bc_data |
| Calke Park,Ticknall (site not precise) | SK32R | 01/01/1883 | 1 | Larvae | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 01/01/1878 | 1 | Adult | vc57_danes_bc_data |
| Repton (site not precise) | SK32B | 01/01/1800 | 1 | Adult | vc57_danes_bc_data |
| Calke Park,Ticknall (site not precise) | SK32R | 01/01/1800 | 1 | Larvae | vc57_danes_bc_data |
| Breadsall Moor, Derby (site not precise) | SK33U | 01/01/1800 | 1 | Adult | vc57_danes_bc_data |