Species: Queen of Spain Fritillary (1, very fresh)

What's Unusual: While scanning a flowery meadow with binoculars to count Clouded Yellows, the observer picked out a very fresh Queen of Spain Fritillary in the field beside the footpath that runs parallel to the A27, south of the Sompting Abbotts School grounds. The encounter was brief: the butterfly hopped over a hedge and could not be relocated despite forty minutes of searching. The editor's response was that British-born Queen of Spain Fritillaries are now emerging, and he urged members to go out and find more.

Context: Queen of Spain Fritillary is a rare immigrant to Britain, so a freshly emerged individual points to local breeding following earlier arrivals. Several observers had been searching for the species during the month. A possible Queen of Spain was glimpsed at Greenway Bottom near Alfriston on 4 September (Report #8425) but did not settle, and a return visit the next day (Report #8440) drew a blank. Another possible sighting was reported at Whitehawk Hill on 25 September (Report #8555). The same Sompting walk also produced 52 Clouded Yellows, including 3 of the pale helice form.

Location: Sompting, field south of Sompting Abbotts School

Species: Brown Hairstreak (1 female)

What's Unusual: A female Brown Hairstreak showed extremely well around a bramble bush, giving the observers a new species for Thorney Island. The editor noted that the 1990–1994 and 2010–2014 county surveys have no records this far west, and that the previous westernmost record was from Cobnor, south-west of Chichester, in 2025.

Context: In a follow-up post (Report #8477, 14 September) the editor described the sighting as outstanding and pivotal: within the past two to three years Brown Hairstreak has colonised the entire Sussex coast, from the Pevensey area to the Hampshire border. Other September records support this spread, including a first-ever East Sussex sighting for one observer at Greenway Bottom (Report #8440), a worn individual at Woods Mill (Report #8531), a female at Warnham Nature Reserve (Report #8484) and one in a Crawley garden tree (Report #8572). Egg searches also proved productive at Friston Forest and Abbot's Wood (see below).

Location: Thorney Island  |  Grid Ref: SU7603

Species: Long-tailed Blue (at least 8 females and 4 males individually identified)

What's Unusual: Following an August sighting, the Felpham observer kept a daily diary of Long-tailed Blues in his garden throughout September, telling individuals apart by their underwing patterns. On 7 September three were watched at close quarters, including two freshly emerged females, with one pair mating for over an hour before roosting on Wild Carrot seed heads. Over the following weeks he distinguished garden-born newborns, the offspring of females that laid on Broad-leaved Everlasting Pea in August, from worn continental arrivals that were seen egg-laying. Further newborns on 25 and 28 September confirmed that a second, unseen female had also laid eggs in the garden in August. The editor described it as quite remarkable that the species turns up in this garden year after year.

Context: With four continental arrivals in seven days, the observer asked whether 100 or more might have made landfall in Sussex (Report #8485). The editor was more cautious, noting that by mid-September there were records from only five locations, that much Everlasting Pea had withered in the heatwaves, and that faded, tailless individuals are hard to identify. Records then spread along the coast: 7 or 8 at Whitehawk Hill (Report #8472), 4 on Tamarisk at Goring beach (Report #8520), egg-laying females on Everlasting Pea at Pevensey Bay (Report #8534), several at Selsey Bill (Report #8548), one at Eastbourne marina (Report #8545), 4 at the Buckle by-pass in Seaford (Report #8569) and 3 in the Lancing Ring area (Report #8570).

Locations: Felpham (garden); coastal sites from Selsey Bill to Pevensey Bay

Species: Clouded Yellow (including many of the female form helice)

What's Unusual: The editor's Storrington garden reached 50 different Clouded Yellows on 18 September, every photograph checked for unique wing markings, and 58 by 22 September (Report #8532). His usual annual total is two or three. He considered 2026 very close to the best Clouded Yellow season in decades, with most recent individuals British-born and the year's six heatwaves a likely factor. On 28 September over 130 were counted on Thorney Island, with more likely in areas not covered. Other large counts included 50+ on Goring beach (Report #8520), 52 at Sompting (Report #8550) and 30–40 at Petworth Park (Report #8479).

Context: Garden firsts came from across the county, including Dallington in north-east Sussex, where eleven were seen over the summer after none ever before (Reports #8431, #8505), and Haywards Heath (Report #8475). In Dallington Forest eight of the nine butterflies seen on one walk were Clouded Yellows (Report #8537). One observer suggested a mass emergence could rival the 500 seen near Birling Gap on 24 September 2009 (Report #8535), and the editor advised checking uncut Lucerne or Red Clover fields. He also remarked that the helice form has been reported more often this year than in any year he can recall (Report #8559). Coastal gatherings are thought to be individuals waiting for suitable winds to cross the Channel.

Locations: Storrington; Thorney Island (SU760030); widespread across Sussex

Species: Small Heath (third brood, 100+)

What's Unusual: A visitor from Nottinghamshire found a few Small Heath flying in late-morning drizzle, but when the sun came out numbers exploded to an estimated 100 or more, along with 30–40 Clouded Yellows rising from the grass. The editor could not recall such a high count for a third brood, and later described the record as unprecedented and yet another county record (Report #8488).

Context: The editor linked the growing number of county records over the past couple of years to climate change. Small Heath were also plentiful along the Ouse Valley between Isfield and Barcombe Mills the following day (Report #8493). The observer also submitted the record partly because Petworth Park is not often covered by recorders.

Location: Petworth Park