Summer peak brings another record count

We missed transect 15 to avoid the uncomfortable heat levels of that week and, as conditions had eased, GH, LN and BG ventured out for week 16’s transect on the morning of Saturday 18th July. 
We had continuous sunshine, with warm and occasionally hot temperatures. The fine conditions were perfect for butterflies and once again they nudged the day’s count up to a new high of 822 (from 21 species) for this 2026 season. Butterflies were seen in good numbers in all 12 sections of our transect route, a sure indication of being at the season’s height. 
This remarkable count was largely due to our recording a massive increase in Meadow Brown numbers, our highest ever count of 450, but  we also saw 211 Gatekeepers and 85 Common Blues (second brood).
A strong supporting cast featured butterflies from 17 other species, including our first Chalkhill Blues of the year (see below) and a single Brown Hairstreak, Britain's last regular butterfly to emerge each season.

Count details
450 Meadow Brown
211 Gatekeeper
85 Common Blue
14 Small Copper
14 Small Heath
7 Chalkhill Blue
7 Purple Hairstreak
6 Brown Argus
4 Speckled Wood
3 Dark Green Fritillary
3 Silver-washed Fritillary
3 Dingy Skipper
3 Marbled White
3 Small Blue
2 Large White
2 Small White
1 Brown Hairstreak
1 Large Skipper
1 Comma
1 Red Admiral
1 Small/Essex Skipper
Count summary
822 butterflies from 21 species.

Chalkhill Blue (Polyommatus coridon) – pictured at head of page

• Males are a dazzling silvery sky-blue, while females are chocolate-brown, sometimes with a dusting of blue near the body.
• This butterfly is closely tied to chalk and limestone grasslands, where its caterpillars feed almost exclusively on horseshoe vetch.
• The caterpillars have a remarkable partnership with ants. The ants protect them from predators in exchange for sugary secretions produced by the caterpillars.
• When to see them in the UK: Typically July-September, with peak numbers usually occurring in late July and August.

More on the wing

Gatekeeper, Stagbury Field - Brian Gardner

Dark Green Fritillary - Liz North

Small Blue, Hither Field -Brian Gardner

Silver-washed Fritillaries - Graham Kenward

Click on photos to enlarge. If you would like to know more about any of the butterfly species mentioned, visit ​butterfly-conservation.org

This week's survey by Graham Harris, Liz North and Brian Gardner submitted to 
​Butterfly Conservation (UKBMS).
​Report by GK, BG & AI. Header photo of Chalkhill Blue by Liz North.