Hampshire and Isle of Wight Butterfly and Moth Society
Hampshire and Isle of Wight Butterfly and Moth Society
| Family: | Nymphalidae |
| Subfamily: | Satyrinae |
| Genus: | Lasiommata |
| Species: | megera |
| Authority: | (Linnaeus, 1767) |
The Wall gets its name from the characteristic behaviour of resting with wings two-thirds open on any bare surface, including bare ground and, of course, walls! Many people will have come across this butterfly on footpaths, especially in coastal areas, where the butterfly flies up when disturbed, before setting again a few metres ahead.
The basking behaviour of this butterfly allows it to benefit from the full warmth of the sun whose rays shine directly on the butterfly, but also get reflected back onto the butterfly from whichever surface it is resting on. This habit allows the butterfly to raise its body temperature sufficiently high for it to fly. In particularly hot weather, however, such basking is avoided and the butterfly may even retreat to a suitably-shaded spot to avoid overheating.
This species was once found throughout England, Wales, Ireland and parts of Scotland. Today, however, is a very different picture, with this species suffering severe declines over the last several decades. It is now confined to primarily-coastal regions and has been lost from many sites in central, eastern and south-east England. In Scotland it is confined to coastal areas in the south-west of the country. It is also found on the Isle of Man and Channel Islands. This butterfly is found in relatively small colonies that are self-contained although some individuals will wander, allowing the species to quickly colonise suitable nearby sites.
| #Individuals | #Tetrads | 2022 | 2023 | Abundance Trend | 2022 | 2023 | Distribution Trend |
|---|---|---|---|---|---|
| 645 | 352 | -45% | 65 | 57 | -12% |
| #Records | #Individuals | Earliest Record | Latest Record | |
|---|---|---|---|---|
| All Records | 5,786 | 10,699 | 14/04/2002 | 10/11/2020 |
| 2023 | 197 | 352 | 20/4/2023 | 7/10/2023 |
| Location | Date | Quantity | |
|---|---|---|---|
| Earliest Record | Pilot Hill transect: Section 8 | 20/4/2023 | 1 |
| Latest Record | Mottistone Down | 7/10/2023 | 2 |
| Highest Count | Hamble | 25/8/2023 | 16 |
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: 39.28
Average #Recorders: 39.28