Chris van Swaay

The White-letter hairstreak (S w-album, Iepenpage) was always very rare in NL, but is now widely distributed over N and C NL. This is partly as we now know how to spot the species, but also true expansion.

2025 so far is a good year for the Southern Small White (P mannii, scheefbloemwitje) on Dutch Butterfly Monitoring transects. With the next generation just starting we hope numbers will peak in September.

Beautifull species

I had no idea where that was (just looked it up), but remember that in D and NL jumps of >200km were not uncommon. And as I said, I am convinced there are more hidden among the photos of last few weeks.

Or this one? x.com/sidwemn/stat...
A male P mannii for sure.
Anyway, there might be (many?) more hidden in the UK photo pages, would be good if all Pieris rapae records would be checked. But I leave that to others (or AI).

Britain has gained a new butterfly!

The long-anticipated arrival of Southern Small White (Pieris mannii) has been confirmed.

Sad. Hope they survive.

This is a classical summer mannii female. First of all the general appearance, esp. the rounded back of the forewing (compared to straight with rapae). Huge square middle spot, apex black goes down to the veign of the middle spot, small short connecting stripe.

First of all the general appearance, esp. the rounded back of the forewing (compared to straight with rapae). Huge square middle spot, apex black goes down to the veign of the middle spot, small short connecting stripe. Classical summer mannii female.

Pieris mannii indeed

When I started butterflying the Speckled wood (P aegeria, bont zandoogje) was restricted to woodlands in a few regions in NL, now it can be found all over the country. 2025 seems to become a good year on Dutch Butterfly Monitoring transects.

When I started butterflying in the 1980s you could see hundreds or thousands of Graylings (heivlinder, H semele) on dry heathlands in August. It could be extremely abundant. But since then numbers went down and 2025 looks like a new low on Dutch Butterfly Monitoring transects.

The start of the flight period for Large Skipper (O sylvanus) on Dutch Butterfly Monitoring transects is more or less unchanged, but peaks lower and ends earlier. Before 2014 numbers end of July would be around half of the peak numbers, now they are close to 0. Numbers 2025 little better than 2024.

Found a good site for Cinquefoil Skipper (P cirsii) in SE France today. With such a beautiful red underside you can understand the Dutch name Rood spikkeldikkopje ('Red Skipper').

On a mud-puddling site hundreds or even thousands of butterflies can gather for minerals (mostly males). During 40 years of butterflying I have see quite a few, but this site in SE France can now be added. Mostly Chalkhill Blue (P coridon).

See filedn.eu/l0TLbjRtm0py... and filedn.eu/l0TLbjRtm0py... (in theory they should be open and visible for you).

The vein feature works where Lafranchis wrote his book, but not in NW Europe. Without an upper side hard to be sure, but the shape of the forewing points to rapae.

Lots of butterflies today on the Col de Champs in SE France, inc A paphia valesina. At least 35 species on 100m or so.

Sorry, dat zou ik niet durven zeggen.

Alternative wording: So 2025 is a bad year, but the previous years were worse. (And of course most of the decline was already before the 90s)

Is 2025 (red lines) a good butterfly year? Yes, on Dutch Butterfly Monitoring transects there are more butterflies than in 2023 and 2024. Numbers almost exactly equal 2022. But look at the 1990s. Compared to then it is a poor butterfly year. Shifting baselines!

In my area on S Veluwe (NL) a new generation of Queen of Spain Fritillary (I lathonia, kleine parelmoer) is out, I counted 13 in a 15min count (plus a Swallowtail P machaon, koninginnenpage). Also many Meadow Brown (M jurtina, bruin zandoogje), top of summer.

Sorry, used an old graph, this is the one from this week, we just reached peak level, number close to normal I would say.

In NL it actually looks quite normal, better than the last few years. Also not at its peak yet, though we are close to 50% females.

Small White (Pieris rapae) Small White from Worthing BN14, UK on July 2, 2025 at 04:36 PM by Ginger Badjie

This could also be a candidate, but again no upperside photo, so hard to be sure: www.inaturalist.org/observations...

But there is only a fraction of the UK Pieris photos on iNaturalist.

Small White (Pieris rapae) Small White from Dover on July 3, 2025 at 01:15 PM by lovelifeactive

This could be one, helas no upperside photo, so not 100% certain: www.inaturalist.org/observations...

A good year for all four Pieris-whites on Dutch Butterfly Monitoring transects. The Southern Small White (P mannii, scheefbloemwitje) seems to be having its highest numbers so far, but also Large and Small White (P brassicae and P rapae) can be seen in large numbers.

As with O sylvanus (Large Skipper) it is one of the examples where a species is expanding its range bc of climatewarming, and at the same time a decline in numbers (bc of lower habitat quality). These things can occur at the same time.

For those who just start with butterflying it will be hard to understand just how abundant the Essex Skipper (T lineola, zwartsprietdikkopje) could be on Dutch butterfly monitoring transects in the 1990s.