Monday 10th March 2014

2014 butterfly list reaches 2 species – and I still haven’t finished 2013!!

Yesterday and today have been our first truly Spring days, and with the warm weather came a considerable emergence of Small Tortoiseshells, Aglais urticae, of which I saw at least 10 yesterday, and of the gorgeous yellow Brimstone, Gonepteryx rhamni, of which I must have seen nearly 20 today!

I now need to hurry with my hypothetical list of species that I should have seen in 2013, but which (metaphorically) slipped through the net, I now come to perhaps one of the most regrettable absentees, the splendid Lesser Purple Emperor, Apatura ilia.

This beautiful species, only marginally smaller than its congenor the Purple Emperor, Apatura iris, occurs in most of the larger woods in the region of northern France and southern Belgium that I frequent, and the only reason for its absence from my list is the fact that I had already left for Scotland by the time it had emerged fully for its summer flight season.

Lesser Purple Emperor, Apatura ilia, f. ilia

A Lesser purple Emperor of the typical form, f. ilia, which has whitish spots on the purple background

In fact, I did in fact see two Apaturas that had the yellowish tinge in flight that is so characteristic of the Lesser Purple Emperor, particularly the yellow form f. clytie, on my one visit to one its most favoured haunts in Belgium, but I only saw them fleetingly from the car and I felt at the time that it would be unreasonable for me to put them on my list. In retrospect, I probably should have done, as they could not have been anything else.

Lesser Purple Emperor, Apatura ilia, f. clytie

A more yellowish individual, f. clytie

In previous years, I have spent many delightful July days in these great forests, marvelling at the beauty of the two Purple Emperor species, often seeing them together feeding on the forest tracks, sometimes sucking up the mineral-soaked water from the damp ground, but often gorging themselves through their bright yellow proboscis on less attractive sources (to us) such as animal dung or dead animals.

Lesser Purple Emperor, Apatura ilia

A Lesser Purple Emperor sucking nutrients from a dead beetle

Based on my observations of these two Emperors of the forest, it certainly seems true that the morning between 10.00 and 12.00 is the best time to find them on the ground; after midday, they tend to retreat to the higher branches of nearby trees, and are harder to find. The video below shows both species of Purple Emperor together, both feeding on dry dung. The Lesser Purple Emperor can easily be recognised by its more uniform sandy-coloured underside, which lacks the bold white band of the Purple Emperor.

Had I counted the Lesser Purple Emperor on my 2013 list of 77 species, plus the other absentees already mentioned, my list would have come to: 86 species.

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Thursday 27th February 2014

Large Chequered Skippers

The next species of butterfly that I missed in 2013 was the Large Chequered Skipper, Heteropterus morpheus, and it was almost a deliberate move on my part not to go to see it. My diary entry for the last time I did see it, in July 2012, reads as follows:

The Large Chequered Skipper, Heteropterus morpheus, is a butterfly with a disjointed distribution, occurring in marshy areas across Europe. There is one region where it can still be found in the Netherlands, but it has declined drastically even there since around 2005, and nobody really knows why. I saw it in profusion in a wonderful wetland reserve called De Groote Peel in 2001 and 2003, but it has since then virtually disappeared from there, with just a few records of lone individuals.

Large Chequered Skipper, Heteropterus morpheus Large Chequered Skipper, Heteropterus morpheus Large Chequered Skipper, Heteropterus morpheus

This year I saw two in a nearby wooded area, but the very limited area in which they could be found was attracting large numbers of butterfly enthusiasts, who despite their love of this rare species, were trampling the vegetation in order to obtain better close-ups.

Large Chequered Skipper habitat

The upperside of the Large Chequered Skipper

Had I seen this species plus the other previously mentioned species that I should have seen, my 2013 list would have been: 85 species

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Tuesday 25th February 2013

Butterflies of the Cranberry Bogs

Following the first really spring-like day here in the Netherlands, I realise that I must hurry on to complete my hypothetical butterfly list for 2013, in which I am adding those species that I should have seen to those that I actually found. My total list came to 77 species, but after that I “added” another five, bringing me to an imaginary total of 82 when I wrote my last diary entry.

Today’s post concerns two butterflies that are relics of the last Ice Age, and which are more at home in Scandinavia, but which just survive in a few tiny, isolated bogs in the province of Drenthe, in the north-east of the Netherlands. Here, creeping over the sphagnum moss in these swampy areas, the extraordinary, stringy plants of Cranberry, Vaccinium oxycoccos, can be found, and it is on this diminutive plant that these two butterflies depend, namely the Cranberry Fritillary, Boloria aquilonaris, and the Cranberry Blue, Vacciniina optilete.

The tiny flowers of Cranberry, larval foodplant of both butterflies

Although I have seen both in previous years, in 2013 I failed to make the journey north to their specialised habitat during their short flight season in June/early July, although I did visit an area in the east of Belgium, where the Fritillary does occur but the Blue does not, as well as a reserve just over the border into France where the Fritillary certainly occurred until recently, but I failed to see it in either place.

Former Cranberry Fritillary habitat which is becoming overgrown

On one occasion when I visited the minuscule bog that I know in Drenthe that still harbours the Cranberry Fritillary, I happened to be holding the butterfly book open at the page with the illustration of the butterfly on it…and one actually landed next to its own image in the book!

A Cranberry Fritillary next to its own image in the book

Cranberry Fritillary, Boloria aquilonaris

The Cranberry Fritillary next to its own distribution map

Much effort has been made to try to link the few remaining bogs in which the butterfly occurs by cutting trees and creating corridors along which the adult butterflies could fly, but with little success, and it now looks as though the species’ outposts in the Netherlands may be doomed. The populations on the high plateaux in eastern Belgium are doing marginally better, but even their future hardly looks secure. However, luckily the species is widespread in Scandinavia, so it is not in immediate danger overall.

The same holds true for the Cranberry Blue, Vacciniina optilete, and its Dutch populations are equally endangered. I tend to see this attractive species in an area of bogland bordered by a low ridge that is covered with Juniper and Crowberry, from which it is possible to spot the rather dark, almost purplish adults fluttering over the wetter ground below.

Cranberry Blue, Plebejus optilete

A male Cranberry Blue showing the dull, purplish blue upperside

Like the Fritillary, the Cranberry Blue is common in Scandinavia, and I have seen many in southern Norway. Here the butterfly may be seen in a wider range of habitats, including rocky moorland.

Cranberry Blue, Plebejus optilete

A Cranberry Blue in southern Norway, where it is much commoner than in the Netherlands

Had I seen these two boreal bogland specialists, plus the five species already mentioned, my 2013 list would have reached: 84 species