Transect 17 was carried out under classic butterfly-counting conditions: hot, humid, and with a sky that alternated between full sun and pockets of cloud. It was ideal weather for butterflies – and pretty good for spotting them too. With just eight transects left in the season, we may well be on course for a record-breaking year.
Gatekeepers, Meadow Browns, and Common Blues continue to dominate, with numbers remaining impressively high for a third consecutive week. It’s shaping up to be a vintage year for many other species too, with Chalkhill Blues, Silver-washed Fritillaries, Purple Hairstreaks, and both Small and Large Whites thriving in this long run of favourable weather.
A particularly exciting find was two second-brood Dingy Skippers – a rare late-summer appearance not seen since 2020. Normally an early-season species, this second emergence may be a response to the extended warm conditions, offering a fascinating glimpse into how climate and habitat interact to influence butterfly lifecycles.
​Each transect now seems to bring a new highlight – what surprises will the next eight weeks hold?

Count details:
​233 Gatekeeper
173 Meadow Brown
  86 Common Blue
  22 Small Heath
  20 Silver-washed Fritillary
  17 Chalkhill Blue
  17 Large White
  14 Small White
  13 Purple Hairstreak
    6 Brown Argus
    5 Holly Blue
    4 Speckled Wood
    2 Dingy Skipper
    2 Ringlet
    1 Brimstone
    1 Marbled White
    1 Red Admiral
    1 Small Copper
Count summary:
618 butterflies from 18 species.
For more info on these species visit
​butterfly-conservation.org

Dingy Skipper (Erynnis tages) – don’t let the name fool you!

• Despite its modest colouring, the Dingy Skipper is actually a day-flying moth lookalike and a master of camouflage, often mistaken for a dead leaf or a patch of bare earth.
• It prefers sunny, sheltered spots with sparse vegetation, often basking with wings outstretched to soak up the warmth.
• Although usually a single-brood species, warm summers can trigger a rare second brood – as spotted in our transect this year for the first time since 2020!

Once again, the heat was on – literally – as we braved sweltering temperatures and sticky humidity for our walk around the 12 sections of our transect in Chipstead Valley. 
Fortunately, while we may have wilted a little, the butterflies positively thrived, with numbers remaining impressively high. As in recent weeks, Gatekeepers and Meadow Browns dominated the count, basking in the sun and jostling for top spot in the tally.
Purple Hairstreaks continued to hold their ground in Hill Wood Field, playing hide and seek among the oaks on the edge of the path.
A seasonal milestone came with the sighting of our first Chalkhill Blues of the year – a welcome return of this chalk downland specialist. And for added excitement, we recorded a solitary Small Blue near the end of Hither Field – perhaps an unexpected second brood individual, defying the calendar with its appearance.
With each walk, the butterfly season reveals more surprises – and with weather like this, the best may be yet to come.

Count details:
267 Gatekeeper
221 Meadow Brown
  85 Common Blue
  19 Purple Hairstreak
  15 Silver-washed Fritillary
  12 Speckled Wood
  10 Small White
    9 Small Heath
   8 Marbled White
   8 Large White
   8 Small Copper
   6 Small/Essex Skipper
   5 Ringlet
   4 Chalkhill Blue
   4 Comma
   3 Brimstone
   3 Brown Argus
   3 Holly Blue
   1 Dark Green Fritillary
   1 Red Admiral
   1 Small Blue
Count summary:
693 butterflies from 21 species.
For more info on these species visit
​butterfly-conservation.org

Chalkhill Blue (Polyommatus coridon) – a specialist of sunny slopes and chalky grasslands:

• Males are a striking pale silvery-blue, while females are brown with orange spots – and both are superbly camouflaged on bare ground.
• This species relies almost exclusively on one plant: Horseshoe Vetch (Hippocrepis comosa), which is the sole food source for its caterpillars, restricting its habitat in Chipstead Valley.
• Males are often seen in large groups, patrolling warm, sheltered areas in search of females, sometimes forming impressive mating swarms.

A true icon of Britain’s chalk downlands, but sadly declining where its food plant habitat is lost.

Brown Argus (Aricia agestis) – small, subtle, and easily mistaken, but full of surprises:

• It may look like a female Common Blue, but the Brown Argus has no blue at all – check for its all-brown wings and twin orange borders.
• Unlike many butterflies, it doesn’t need one specific host plant – caterpillars happily munch on various geranium species.
• It can produce two or even three generations in a good summer, making it a surprisingly fast breeder for its size.

GH, LN and BG walked transect 15 choosing a morning just before the third heatwave of the summer rolled in. Even then, our walk-around certainly felt warm in the constant sun with barely a breeze.

The butterflies, however, were loving it. We recorded another very busy count with an exceptional 728 individuals, our third highest since 2019. The sudden drop-off in Marbled Whites was more than compensated by the dramatic surge in Gatekeeper numbers, leaping from 88 last week to a remarkable 305. The Meadow Browns have held at a roughly constant high level for the past three weeks, and we saw increased levels of Small Whites, Common Blues and Silver-washed Fritillaries.
A special highlight came while observing the Purple Hairstreaks flitting about Hill Wood Field’s trees.  Liz was suddenly distracted by spotting a large high-flying butterfly that she identified as a Purple Emperor, and moments later Graham H confirmed a second one as it flew over our heads. These two sightings were the first Purple Emperors ever recorded on our transects since we started back in 2016.

Count details:
​ 305 Gatekeeper
174 Meadow Brown
  47 Common Blue
  38 Ringlet
  34 Large White
  30 Marbled White
  26 Small White
  14 Silver-washed Fritillary
  12 Purple Hairstreak
  11 Small/Essex Skipper
  (inc. 1 Small and 2 Essex Skippers)
    9 Brimstone
    7 Dark Green Fritillary
    6 Comma
    5 Speckled Wood
    3 Small Copper
    2 Peacock
    2 Purple Emperor
    2 Purple Hairstreak
    1 Brown Argus
Count summary:
728 butterflies from 18 species.
​For more info on these species visit
​ butterfly-conservation.org

Common Blues  (Polyommatus icarus)
Caught in a quiet moment, this pair of Common Blues is doing what summer butterflies do best – ensuring the next generation.

• When their wings are open, males are bright sky-blue, while females are often brown with a dusting of blue – making them trickier to identify.
• Mating can last up to an hour, and the female stores sperm to fertilise eggs over several days.
• Their caterpillars have a surprising ally: ants often ‘farm' them, protecting them in exchange for sugary secretions.

Love, protection, and ant partnerships – all in the life of a Common Blue!

Large Whites (Pieris brassicae)
This elegant duo of Large Whites, often called ‘cabbage whites’, is doing more than dancing – they're continuing a legacy of garden notoriety.

• Female Large Whites can lay over 600 eggs in their lifetime, often on brassicas like cabbage, kale, and broccoli – hence their fame (or infamy) with gardeners.
• Mating takes place soon after emergence, with males transferring a waxy plug to prevent the female from mating again.
• Their caterpillars are gregarious and toxic to predators, thanks to the mustard oils in their host plants.

Romance, strategy, and a touch of chemical warfare – this couple is anything but ordinary.

Gatekeepers (Pyronia tithonus)
This affectionate pair of Gatekeepers isn’t guarding anything – except perhaps the summer hedgerows they call home.

• Males are often seen basking in sunny spots along paths and field edges, defending small territories with surprising zeal.
• Courtship is brief: males patrol and pounce quickly, and if the female is receptive, mating may last several hours.
• Unlike many other butterflies, Gatekeepers have two small eyespots on each forewing, possibly helping to deter predators by mimicking larger animals.
• A familiar sight in high summer, these fluttering ‘gates' to the countryside are as romantic as they are territorial.

Transect 14 of our 26-week season was carried out by GH, LN and BG on a warm, sunny morning – tempered by a strong breeze. The butterflies, however, seemed unbothered. In fact, they turned out in spectacular numbers, continuing the trend of an exceptional early summer.
The usual crowd of Meadow Browns, Marbled Whites and Ringlets led the way once again, but this week they were boosted by dramatic increases in Gatekeepers and Large Whites. Perhaps most exciting was the unexpected burst of newly emerged Purple Hairstreaks, glimpsed dancing in the trees at the top of Hill Wood Field – a rare treat, as this species often stays elusive in the high canopy.
This transect shattered our previous records: we logged 22 different butterfly species in a single walk, beating our previous best of 18. Even more impressively, our cumulative total for the season so far has reached 3,331 butterflies – already beating the totals for several entire past seasons … and we’re only halfway through!

Count details:
179 Meadow Brown
129 Marbled White
  88 Gatekeeper
  59 Ringlet
  39 Small/Essex Skipper
  (inc. 4 Small and 5 Essex confirmed)
  27 Large White
  21 Purple Hairstreak
  14 Common Blue
    9 Small Copper
    6 Speckled Wood
    5 Comma
    5 Dark Green Fritillary
    4 Small White
    2 Small Heath
    2 Brimstone
    2 Brown Argus
    2 Silver-washed Fritillary
    1 Green-veined White
    1 Holly Blue
    1 Large Skipper
    1 Peacock
    1 Red Admiral
Count summary: 598 butterflies from 22 species. 
​For more info on these species visit
​ butterfly-conservation.org

Dark Green Fritillary (Argynnis aglaja) – a fast flier with a taste for the wild.

• Despite the name, it’s not very green – its name comes from the greenish sheen on the underside of its hind wings.
• It’s one of the UK’s speediest butterflies, zipping across grasslands in a blur of orange and black.
• Its caterpillars rely on violets – especially Dog Violet – as their sole food source, laying eggs near tufts where the larvae can safely hibernate over winter.

GH, LN and BG tackled transect 13 under warm skies and a lively south-westerly wind – and the butterflies didn’t disappoint. From the first step, the air was alive with fluttering wings, thanks to swathes of Marbled Whites and Meadow Browns, with strong back-up from Ringlets and Small/Essex Skippers.
The final tally? An impressive 601 butterflies – lifting our already stellar season even higher and equalling our season-best for species variety with 18 different butterflies recorded. While still a way off the 1,207 record from the legendary ‘super season’ of 2019, the trend is promising.
The day’s showstopper was a quartet of Silver-washed Fritillaries dancing through a sun-drenched glade at the base of Coneyboro Hill. There was also a quick flash of Purple Hairstreak high in the oaks of Hill Wood Field, and our first Gatekeeper of the year.
And beyond the transect? White Admirals are making rare appearances around our area – two were seen near the elm glade in Banstead Woods, another in Lord’s Field and one even gracing a volunteer’s garden pond!

Count details:
228 Marbled White
166 Meadow Brown
  81 Ringlet
​  67 Small/Essex Skipper
 14 Dark Green Fritillary
   9 Large White
   8 Brimstone
   4 Silver-washed Fritillary
   4 Small Copper
   4 Speckled Wood
   3 Comma
   3 Common Blue
   3 Small White
   3 Small Heath
   1 Gatekeeper
   1 Holly Blue
   1 Peacock
   1 Purple Hairstreak
Count total: 601 butterflies from 18 species.
For more info on these species visit
​ butterfly-conservation.org