Tag Archives: white-letter hairstreak

It’s time to Hunt the Hairstreak

Greyis butterfly with white lines and an orange dot, on a leaf.
Purple Hairstreak. Photo: Malcolm Wemyss

Dorset has four of the five Hairstreaks: the Green, the Brown, the Purple and the White-letter. The Green is out earlier in the year, but the White-letter and the Purple are out now, and we need help recording them for different reasons. Continue reading

White-letter Hairstreak Harman’s Cross

White-letter Hairstreak on a thisle flower

White-letter Hairstreak. Photo: David Parish

David got this great shot while out looking for this butterfly with Brian Arnold at Harman’s Cross on 06/07/2017. Brian says:

“Today we searched for a while looking up at the Elm trees but did not see any, but I then walked to the east most point of the Elm trees where there is a small patch of thistles in the field, and after a couple of minutes spotted a small dark coloured butterfly which was a White-letter Hairstreak. I have not seen them near the ground there before, previously they have been high in the Elm trees or very occasionally in the lower branches. My last sightings were 2 years ago when I saw 2, and 3 years ago when I saw 5 Today we saw 2 down low in the patch of thistles in the field. The first one flew away quite quickly and back up into the Elms. The second stayed down low for about 20 minutes giving us plenty of time to get photographs before it also flew away.”

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White-letter Hairstreaks at Alners Gorse

White-letter Hairstreak on a bramble flower

White-letter Hairstreak. Photo: David Simmonds

Caught at our Alners Gorse Butterfly Reserve on 25/06/2017.

This butterfly is now quite rare, having been hit hard by Dutch Elm Disease: it’s caterpillars feed on elm. Alners Gorse is the only site in Dorset where you stand a good chance of seeing it, though we’d really like to hear of sightings in any other parts of Dorset.

White-letter Hairstreak – Alners Gorse

White Letter Hairstreak

White-letter Hairstreak. Photo: Mark V Pike

The White-letter Hairstreaks are out at our Alners Gorse reserve with at least ten individuals seen on the 05/07/2015 along the Elm and Ash hedgerow.

Keep an eye out wherever you are in Dorset for these high-flying butterflies, particularly in areas where Elm abounds and Bramble flowers flourish nearby – send us your sightings!

The search for the White-letter Hairstreak

White-letter Hairstreaks have been very under-recorded in the current five-year recording cycle, and as 2014 is the last year of it, we need to go looking for them this summer.

Google Earth map

Google Earth map

The red markers on the map above show the seven records which have been received since 2010. The yellow markers show those gathered between 1995 and 2009, during which time the White-letter Hairstreak was recorded in 47 locations. We do not think the butterfly has declined this drastically, but that there has been a lack of recording. Click here for a spreadsheet listing all the squares involved. To see much more detail, open this link to Google Earth (you will need to have the free Google Earth software on your computer for this to work) which allows you to zoom right in to understand the position of the relevant kilometre squares.

White-letter Hairsteaks breed on elm trees, and were very badly hit in the 1960s and 1970s when Dutch elm disease wiped out two-thirds of the country’s elm trees. They prefer wych elm, but may also use English elm and smooth elm.

They are not easy butterflies to spot, and it has been suggested that the problem is that recorders are searching at the wrong time. The best time to look is the last week of June and first week of July on, or very near, elm trees, when the males will be flying around in the tops of the trees. There cannot be any confusion with the Purple Hairstreak as, although that butterfly flies in a similar fashion, it is not out this early in the year. In July you may find the butterflies lower down, nectaring on flowers such as creeping thistle, bramble, ragwort, marjoram and hemp agrimony.

White-letter Hairstreak

White-letter Hairstreak. Photo: Rob

White-letter Hairstreak

White-letter Hairstreak. Photo: Mark Pike

White-letter Hairstreak

White-letter Hairstreak. Photo: Mark Pike

You might actually have more luck spotting the caterpillar. When it is at its biggest in June, it is 15-16mm long, and though it is very well camouflaged, it is sometimes posible to stand under the tree and look up when the sun is shining on the leaves and see the dark shape of the caterpillar in silhouette. You may also be able to spot where the leaves have been damaged by the caterpillars eating them, but there are also around five species of moth caterpillar which may be doing this – however, it might at least help you to narrow down where to look more carefully.

If you do find any White-letter Hairstreaks, please let us know. You can use the sightings form on this website, or tell us what you have seen via our Contact Form, and we’ll get back to you. If you can send us a photograph, that would be even better.