Winter Blues

[NickMorgan]

A bit of a mystery! We have had two people reporting a blue butterfly in their garden early November in the same village. There are only two choices up here (south-east Scotland) - Common Blue, which has only recently started to produce a second generation in September and Holly Blue, which have only been recorded here in significant numbers in the last four years.
So, I am wondering if anyone further south with more experience of these species has any idea what it could have been. Personally, I am going for a Holly Blue, as that is more of a garden butterfly. Do they occasionally produce a third generation in a year?
Thank you for any help.

[David M]

Long Tailed Blue?

[millerd]

Hi Nick!

Both Holly Blues and Common Blues regularly produce a third brood in the south of England, and I have had sightings of both species on my patch near Heathrow during the first half of November this year. Holly Blues in particular are seen here in most Novembers these days, but in this particularly warm autumn, their third brood was actually a bit earlier than it usually is with most butterflies flying in late September/October.

I'm guessing that Holly Blues are always double-brooded, even at the northern edge of their range, whereas Common Blues have (as you mentioned) only recently started to do this up there. Consequently, under the influence of a long spell of warm weather stretching into autumn, it is more likely that the Holly Blue might produce a third brood. The fact that the sightings were in gardens also tends very much to point to this species, and if those gardens contained flowering ivy, then I'd say this becomes a near certainty.

Just a personal opinion - there may be other insights out there!

Dave

[Padfield]

Holly blue is certainly the more natural choice, though as something unusual is clearly going on here it's difficult to be confident (and David's suggestion of long-tailed blue is therefore a possibility). Growing up in Woodbridge, in Suffolk, I regularly saw holly blues in November in the garden, but never common blues. In contrast, it is common (and Adonis) blues that persist into November in Switzerland, rather than holly blues. I think the main take-away from this is that there exist people who can't tell a holly blue from a common blue. This needs to be corrected.

Guy

[NickMorgan]

Thank you for your replies David, Dave and Guy,
I wonder if there have been any records of Long-tailed Blues in Scotland. I haven't heard of any, but it isn't beyond the realms of possibility. I have head of chrysalises arriving in supermarket bags of peas!
Yes, Holly Blues have two very definite generations here, just as the books say they do down south. It is really interesting that for years I have received reports of either one or two Holly Blues a year all from a couple of coastal villages, then three years ago quite a number of reports came in from one of those villages. Last year they were seen in a radius of about 10 miles from that village and this year they have continued to spread probably about another 10 or 15 miles. Naturally, people tend to send in records of exciting butterflies, but there have been a lot of Holly Blues spotted this year.
Interesting that Dave and Guy have both seen Hollies in November in southern UK (even if Dave has also seen Common!) I will ask about ivy in the garden - that is a good point.
Yes, I am working on people recognising the difference between Holly and Common Blues. I am working even harder to try to get people to record what they have seen by some means or other. It is frustrating when quite a few naturalists I know just spend ages chasing and photographing butterflies, but don't keep any records!