70.012 BF1711  –  Geometridae –  Sterrhinae – Idaea trigeminata – Treble Brown Spot – (Haworth, 1809) Adult Macro:  CAT 1 – Distinctive species unlikely to be confused with others –       PDF Icon – click for Adult Macro Verification Guidelines

Brown –  Significant Record / Very Rare / Vagrant    
Taxonomy:   Macro   >>  Geometridae  >> Sterrhinae
ID Difficulty:  green  – easy to identify, generally distinctive and unlikely to be confused with other species.
ID pointers: Unmistakable and strikingly marked – as the name suggests, there are three brown spots in the lower area of the trailing edge of the forewing.
Distribution:  (First record: 1980 )  –  (Last record: 5 July 2025 at Darwin Forest, Matlock )  –  Current status unknown possibly a vagrant – 1 record in 1980. During recent moth record verification, two 2023 records were discovered from Darwin Forest, near Matlock by Dave Evans. One on 26/07/2023 & one on 27/7/2023. Possible re-catch of the same moth. These are the first reported since 1980. Another record from Darwin Forest on 5/7/2025 (seems this species maybe established at this site albeit a small isolated population)
Flight Period: May /  June /  July /  –  On the wing – May – July Moth Activity: Nocturnal   – and is attracted to light Photographed: Yes –  Photographed By: Dave Evans  © All Rights Reserved
*** Last updated on 26 July 2025 by TD ***
Wingspan: 23-25mm
Forewing: 10-11mm
Food Plant: Knotgrass and Ivy.
Last Recorded Year: 2025
First Recorded Year: 1980
Last Recorded By – Dave Evans
Last Recorded General Area – Darwin Forest, Matlock

IMAGES BELOW:  Darwin Forest – 26/7/2023 – Dave Evans © Darwin Forest (2025) – Dave Evans©

 
 

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Distribution Map for Idaea trigeminata

Found 6 records
    ↳ 1 from After 2025
    ↳ 2 from 2020 - 2024
    ↳ 3 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.

******* Choose ONLY one at a time, of either Monad, Tetrad or Hectad Distribution - each has it's own set of data. Also, the distribution maps cover ALL recorded data. *******

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.

Land-cover * shows the variety of land-cover within the VC57 area, based on the CORINE (Coordination of Information on the Environment) forty-four thematic classes of land-cover. This will show, to a greater or lesser degree, the number and variety of moths found in different land-cover types. The UK continues to operate within the Copernicus programme, with the UK Centre for Ecology & Hydrology (UKCEH) providing Corine Land Cover (CLC) datasets for the UK and its territories.


NBN Atlas UK Distribution for – Idaea trigeminata

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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.

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Monthly Records By Year: Idaea trigeminata
( data includes both Larvae and Adult Stages )

Monthly Counts By Year: Idaea trigeminata
( data is based on 'Adult' stage records only. )


First/Last Recorded Dates: Idaea trigeminata
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: Idaea trigeminata
( All data includes both Larvae and Adult Stages )
Annual Growth Rate (AGR): Idaea trigeminata
AGR: 0%   |   Total % Change: 0%


CUSUM Analysis: Idaea trigeminata
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 23 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 7 (July) 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 2023, 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: Idaea trigeminata
( data includes both Larvae and Adult Stages )

Flight Periods – Indicative –vs– Recorded Data
Idaea trigeminata
( 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 - Idaea trigeminata – 6 records available

Listed by Year - descending - scroll across to see all table columns

TaxonSite NameTetradYearDateCountStageSource
Idaea trigeminataDarwin ForestSK26X202505/07/20251adultvc57_irecords_extract
Idaea trigeminataBelperSK34U202312/06/20231adultvc57_irecords_extract
Idaea trigeminataDarwin ForestSK26X202326/06/20231adultvc57_irecords_extract
Idaea trigeminataThe Meads, Shipley Park, HeanorSK44H201913/07/20191adultDanes_2019-2021
Idaea trigeminataJohnnygate, Common Side, ChesterfieldSK37C199001/08/19901Adultvc57_danes_bc_data
Idaea trigeminataJohnnygate, Common Side, ChesterfieldSK37C199014/07/19901Adultvc57_danes_bc_data

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