Hampshire and Isle of Wight Butterfly and Moth Society
Hampshire and Isle of Wight Butterfly and Moth Society
| Family: | Lycaenidae |
| Subfamily: | Polyommatinae |
| Genus: | Aricia |
| Species: | agestis |
| Authority: | ([Denis & Schiffermüller], 1775) |
Unlike most other "blues", the Brown Argus has no blue scales on its upperside, both sexes being primarily brown in colour as its common name suggests, although the butterfly does exhibit a blue sheen when at certain angles to the light. Both sexes have beautiful orange spots on the upperside of both forewings and hindwings. This widespread species can be found south of a line between Dorset in the west and South-east Yorkshire in the east, along with colonies in Derbyshire, North Devon, East Cornwall and West Cornwall. It is also found in north and south Wales, but is absent from central Wales. This species is also absent from Scotland, Ireland and the Isle of Man. This species occurs in small, compact colonies, and is not a great wanderer, only travelling a couple of hundred metres, at most, from where it emerged.
| #Individuals | #Tetrads | 2022 | 2023 | Abundance Trend | 2022 | 2023 | Distribution Trend |
|---|---|---|---|---|---|
| 1955 | 6383 | +226% | 149 | 237 | +59% |
| #Records | #Individuals | Earliest Record | Latest Record | |
|---|---|---|---|---|
| All Records | 23,084 | 70,107 | 08/04/2002 | 31/10/2005 |
| 2023 | 1,927 | 6,383 | 7/5/2023 | 9/10/2023 |
| Location | Date | Quantity | |
|---|---|---|---|
| Earliest Record | Magdalen Hill Down Original transect: Section 10 | 7/5/2023 | 1 |
| Latest Record | Portsdown Hill | 9/10/2023 | 1 |
| Highest Count | Broughton Down | 9/8/2023 | 82 |
One of the issues with 'raw' trend data is that there is inherent bias based on the number of recorders. For example, the number of individuals and populated tetrads recorded are likely to increase if there is an increase in the number of recorders. In order to remove this bias, the normalised trends use data that has been recalculated using the average number of recorders over the trend period. This normalisation gives a much better picture of the true trends.
Average #Recorders: 105.96
Average #Recorders: 105.96