This report presents an analysis of butterfly sightings data for the month and identifies reports that are notable due to unusual timing, abundance, rare forms, behaviour or other aspect of interest.
The analysis presented on this page was produced by Claude, an AI assistant developed by Anthropic, as part of an exploratory exercise to surface interesting patterns and insights from our butterfly sighting records. The results are intended to demonstrate the potential of AI-assisted analysis in citizen science contexts.
AI-generated outputs can contain errors or misinterpretations and while the analysis has been sample checked by human reviewers, the Editor may not agree with all of the comments. The findings should not be treated as definitive scientific conclusions and are best understood as indicative insights. If you spot any errors please let us know at webmaster at sussex-butterflies.org.uk.
Species: Camberwell Beauty
What's Unusual: A Camberwell Beauty appeared in the observers garden and was it immediately recognised as the observer had previously lived in Italy. No photo was taken as the butterfly vanished as quickly as it had appeared. The editor's reaction was simple surprise, noting that none had been recorded in Sussex for several years, making this one of the rarest single sightings of the month.
Context: Camberwell Beauty is a scarce immigrant to Britain, usually turning up in late summer on the east coast of England and Scotland, occasionally drifting further west. At this time of year, individuals typically seek out Buddleia to build up reserves before hibernation, so gardeners with Buddleia were encouraged to keep watch. The editor also noted that this record brought the county's confirmed butterfly species list for the year to 50.
Location: Palehouse Common
Species: Chalk Hill Blue
What's Unusual: Several sites reported exceptional Chalk Hill Blue counts this month. Horseshoe Plantation produced over 1,400 in a single visit, described by the observer as the most productive butterfly outing of their life. Stoke Bottom, on the Amberley Downs, held an estimated 1,500–2,000 individuals, with steep south-facing slopes described as a mass of flickering movement. At Windover Hill, 193 were counted along a single stretch of track. Most striking of all was Friston Gallops, where a long-running habitat restoration project recorded 2,508 butterflies of 21 species on 23 July, including 390 Chalk Hill Blue and 8 Adonis Blue, up from just 289 butterflies of 15 species recorded on the same transect in April.
Context: The Friston Gallops figures reflect several years of grazing and scrub-clearance work following the site's decline after Rabbit numbers collapsed due to the RHDV2 virus. The wider abundance of Chalk Hill Blue across the county's chalk grassland sites points to a strong breeding season, aided by the extended hot, dry conditions experienced through the month.
Locations: Horseshoe Plantation; Amberley Downs (Stoke Bottom); Windover Hill; Friston Gallops
Species: Duke of Burgundy (second brood)
What's Unusual: A fresh-looking male Duke of Burgundy was found at Chantry Hill, in an area where the Storrington Conservation Society had carried out winter habitat work. The observer had not realised the species could produce a partial second brood, and the editor considers this may be the first-ever second-brood Duke of Burgundy recorded in Sussex.
Context: Duke of Burgundy is normally single-brooded in Sussex, flying in spring. A confirmed second generation would be a significant addition to the county's records and, like the county's expanding second-brood Dingy Skipper records, may reflect the influence of a warm season on butterfly life cycles. The individual could not be relocated later the same day.
Location: Chantry Hill
Species: Grayling (1 male)
What's Unusual: Grayling failed to appear at Deep Dean, its only known Sussex colony, through repeated dedicated searches from mid-July onward, prompting growing concern among regular recorders. A single fresh male was finally found on 27 July, landing on the observer, the first confirmed sighting of the year at the site. Further searches over the following days still failed to turn up any additional individuals.
Context: The 10-year average first-sighting date for Grayling at this site is 16 July, with a range of 9–22 July, making this year's emergence markedly later than usual. Butterfly numbers generally were reported as down across the valley this year. As Grayling exists at only one known colony in Sussex, the eventual sighting was treated with considerable relief, although recorders remain concerned about the health of the population.
Location: Deep Dean
Species: Purple Emperor (30+ in a day)
What's Unusual: A mating pair of Purple Emperor was observed low in an oak tree for four hours and two minutes, well beyond the species' average pairing time of around three hours and forty minutes. Over 30 individuals were seen at the site on the day, including other pairs that tumbled into the brambles below as already-mated females rejected further suitors.
Context: While the day's count was strong, it was reported as significantly down on 2025's exceptional Purple Emperor season, with the observer noting that reduced quantity was more than made up for by the quality of behaviour witnessed. Continued hot weather was expected to compress the flight season into a shorter window than usual.
Location: Knepp Wildland
1 July 2026
The observer estimated Sussex has seen more Painted Ladies this year than at any time since the "monster invasion" of 2009, likely in the low hundreds of thousands county-wide. A British-born individual, probably less than 24 hours old, was found in the garden the same day.
3 July 2026
Only the observer's second-ever White-letter Hairstreak, found well away from any Elm trees, among a count of 22 species that also included an early Clouded Yellow for the site.
3 July 2026
Three second-brood Dingy Skipper found at Steyning Rifle Range, which the editor believes is most probably the earliest Sussex record for the second brood, well ahead of the usual mid-July to mid-August window.
5 July 2026
27 Wall Brown, including at least 6 females, counted at Lancing Ring and Steep Down, a total the editor described as astonishing for so early in July.
14 July 2026
A Brown Hairstreak seen near the top of Chantry Hill was a first for a recorder who has surveyed the site for many years, prompting a good-natured response from the editor, who has also never recorded an adult there despite extensive effort.
19 July 2026
A Wood White egg laid in Crawley on 10 June was taken into care after the council began cutting the site, hatched on 20 June, and emerged as an adult female 29 days later, before being released back at its site of origin.
24 July 2026
The garden's first Brown Hairstreak of the year appeared 21 days earlier than in previous years and was seen egg-laying on a plum cherry, part of a wider spread of unusually early and widespread Brown Hairstreak reports across the county this month.
26–27 July 2026
Wood White found on successive days at Verdley Wood, alongside records from the previous year and spring, suggesting an established small colony. The site is managed for Pearl-bordered Fritillary, and one contributor noted it may be one of very few UK sites supporting both species.
25–31 July 2026
Up to three or four Long-tailed Blue reported across several visits to Whitehawk Hill through the second half of the month, alongside reminders from the editor and contributors about the importance of not trampling the site's Everlasting Pea.
July 2026 was another remarkable month for butterflies in Sussex, shaped strongly by prolonged hot, dry weather, and characterised by:
