So far the mean number of butterflies per 1000m on Dutch Butterfly Monitoring transects mirrors 2019 and 2022. But also clear we will have more that 2023 and 2024, which were the worst years since 1990.

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.

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.

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.

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

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).

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').

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.

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.

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.

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.

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.

The next generation of Southern Small White (P mannii) has started, I just made this photo in the garden. You notice them as they are a bit smaller than Small Whites and have a slightly different way of flying. This generation should have a large and dark square middle spot.

The mean number of butterflies on Dutch Butterfly Monitoring transects is now very low as compared to other years since 1990 (though 2024 was worse). With such low numbers flowers in gardens also stay empty: there are simply no butterflies around to visit them.

As a true climate opportunist the Short-tailed Blue (C argiades, staartblauwtje), which arrived in NL in 2009, profits from hot and dry summers caused by climate change. Numbers on Dutch Butterfly Monitoring transects now higher than ever.

We had a large 1st gen of the Common Blue (P icarus, icarusblauwtje) on Dutch Butterfly Monitoring transects. But where the 2nd gen is usually twice as big, in 2025 it was even smaller, probably because of poor foodplant quality as a result of dry conditions in spring.

Up to July numbers of Red Admiral (V atalanta) were good on Dutch Butterfly Monitoring transects, but since then they plumeted and now mid-August we have a negative record, as never before there were so few of them counted. This is most probably linked to poor nettle-quality.

Clouded and Pale Clouded Yellow (C hyale+crocea, gele en oranje luzernevlinder) are migrants in NL and show large year-year fluctuations in density on Dutch Butterfly Monitoring transects. Before 1980 C hyale was considered more abundant, now it is C croceus. 2025 up to now.