Purple Hairstreak

[Dave McCormick]

I have been looking all over where I live (which is still not all known about when it comes to butterflies and moths) and I noticed a forest which 1/3 of it is oak trees, plus there is a few huge oak nearby it too. I wanted to see if any chance of finding purple hairstreak here if it does exist, its quite rare in Northern Ireland. Can anyone tell me when the best time to look would be and any tips on spotting one?

[millerd]

My personal experience is to go out on a fairly still sunny evening (after 6) from the second week of July onwards (up to the start of September), and gaze at the tops of oak trees. I've seen them around trees both big and small, isolated and within woodland. They dart about and chase each other around the tree tops and can be spotted silouhetted against the sky in groups, sometimes five or more. They will pause to bask and can sometimes be examined through binoculars. They will stop on other neighbouring trees as well, particularly ash.

Close-up views are very difficult to engineer, I find - I have only ever stumbled on them by chance, and always at other times of the day, a singleton on a bramble flower, a female laying on the tip of an oak branch at head hight. You might be lucky to find a newly-emerged individual low down in the morning, as I believe they pupate at ground level.

Dave

[Padfield]

I agree - to check an area for purple hairstreaks when you are not sure they are there the best thing is to use the early evening treetop method, because it's there that they are most conspicuous, and often in good numbers. Then, when you have found them, you can hope for lower shots (females come down low to lay and males come to minerals along tracks, especially where horses or bikes have turned the dirt and rutted the surface). Both sexes (I think) will take honeydew, sitting on leaves at any height, slowly rotating in classic hairstreak fashion.

HOWEVER, my own experience this year is that the very best way to find new colonies is to look for eggs in the winter. I found loads of new locations for the species simply by checking every suitable oak every time I went for a walk. Suitable oaks (here in CH, at least) have few residual clingy leaves and rather large, healthy-looking buds. Lichen and algal growths on the branches are generally a bad sign. Search healthy trees on the sunny side of woods, on branches in the sun, not the shade. I found eggs on west-facing branches where these reached out and got lots of evening sun, but more often on the south side of trees. Obviously, I didn't look high up in trees, but I found very good numbers of eggs at about chest to head height and have often seen females come down for laying. Most of the eggs I found were on youngish oaks - often bushes rather than trees - but some were on ancient trees.

Guy

[Dave McCormick]

Thanks both, well if I do see what could be one, any shot that you can make out what it is will do, doesn't have to be a great shot. I'll have a look around at the start of July onwards around all the oak I know of and see if any are about.

Guy, thanks for the egg info, might give that a go this winter even if I do find adults. I only know a few old oak trees (one is about 450-500 years old and other is about 600 years old, very wide trunk and really tall so might be harder to look on those)

In a few weeks I am going to Rostrevor in Co Down to look for Silver Washed Fritillart, it ha s large oak woodland which I can scan to see if any Purple Hairstreaks there, however being a National Nature Reserve, I think if they were there, someone might have seen them already well I'll look about this year and see what I can find. So far this year I have found the micro moth Acleris abietana in a forest about a mile from my house, the first two known Irish records of it, but I suppose moths are different as they are night flyers many and butterflies are generally day flying and should be easier to find.

[millerd]

This is probably what you'll see...

Dave

[Dave McCormick]

Hi Dave,

Thanks for the image, going to look tomorrow to see if any are about. Incidentally, someone I was chatting to, he was moth trapping in an oak wood and one came to his trap, he said they can be attracted to moth trap lights, anyone else experienced that or know why this could be? I thought the butterfly gets dazed when resting when the light is shining and when dazed, fly towards it.

[Eris]

My ones...(Well not exactly mine - I am just the landlady for their trees ) , are on both the old trees and the younger trees, and of course if they are on the younger tree an they are far closer to the ground and easier to see close up. The ones in the old oaks are right at the very top and only viewable with binoculars.

Interestingly enough I noted that there were 3 still flying around chasing each other late last evening at just after 9pm which was overcast and cloudy as well, so they are not only flying on sunny evenings. They were flying around during the day as well, but would take cover during any time the wind was a bit strong.

BTW do wasps take adult hairstreaks?

[millerd]

I should think it's entirely possible - I witnessed a wasp decapitate a newly emerged Peacock with absolutely no provocation whatsoever last year.

Dave

[Neil Hulme]

And I watched a wasp kill and rapidly eat one of the infamous Black-veined Whites of Old Stockbridge Down .
Neil

[Lee Hurrell]

Since I joined the site I have heard a few mentions of something infamous that went down at Stockbridge. I take it it was a introduction of Black Veined White?

Cheers

Lee

[Eris]

Hummmm.... lots of wasps around here at the moment, and I was seeing them up in the trees, and I saw one seem to investigate one of the hairsteaks, but the hairstreak cleared off pretty rapidly, so I was not sure if it was actually after the butterfly of it was just checking it out.

[Trev Sawyer]

Kipper,
Wasn't that the Phanton Raspberry Blower of Old Stockbridge Down?
Sorry, I'm back to "The Two Romnnies" again

Trev