www.ukbutterflies.co.uk

Virtually all the Meadow Browns I am seeing now (late August) are females. It is thought they generally mate on the first day of emergence but where are the males? Do they mate at times when we don't usually see them, in the early morning or late evening and/or are the males hiding in deep vegetation?

It is a complete mystery to me why adult females and not males are seen so late in the year unless perhaps as a means of dispersal.

ATB

Peter

This is interesting...
In hot Mediterranean climates (eg Portugal) and some parts of Greece, the females actually aestivate during the high heat of mid-summer, before reawakening to lay eggs later in the year. I wonder if this occurs to a lesser degree in this country also - it may be that this year's heatwave has made this more noticeable in the UK this year. Presumably the females pair up before entering aestivation, although that would suggest very long term viability of the male meadow brown semen, unless they are able to fertilize eggs and the female can then arrest their development.
I am sure someone on here will have more knowledge on their biology!

Yesterday, about 12:30, I disturbed a pair of coupled Meadow Brown. They were in a thick clump of marram grass and fluttered away still joined. I was preoccupied and didn’t give it a second thought, but this post has made me realise that I don’t recall seeing Meadow Brown mating before.

I mainly see females at this time of year, often in egglaying mode in cut grassland. But there is still the odd male about. Some people talk as if this is a partial second brood, as they tend to only see fresh-looking individuals. But transect graphs show this is not the case and it is just the last of the summer's protracted emergence. It's as if the proportion of fresh to worn individuals changes towards the end of the season

The aestivation theory could well have some value. I've noticed reports of fresh looking Meadow Browns in the south of England well after the last in south Wales have disappeared.

Of course, temperatures are consistently 4 or 5c warmer in the south and SE of England than in Wales, so maybe there's a 'tipping point' which encourages certain butterflies to take a temporary 'sabbatical'?

That tipping point is clearly not normally reached in my part of the world, as Meadow Browns are generally spent completely by the end of August.

Thanks Pete. I suspect you are right that females might aestivate to some extent in hot weather in the UK. I have read that females can live for some months in the warmer climes in Europe and egg-laying can be delayed by up to 2-3 months. See http://journals.plos.org/plosone/articl ... ne.0111955 . Do females expend less energy than males in locating mates, for example, which may prolong their lives?

Thanks Wolfson. I regularly see mating pairs, perhaps 2 or 3 a year, in the middle of the day.

Thanks Bertie. The protracted emergence of females seems to be the consensus but do the latest emerging females find any males?

Thanks David. It would not surprise me if there is a tipping point in temperatures above which females may decide to aestivate, which may be more evident this year in the UK because of the recent heatwave.

ATB

Peter

This has come up before. I see good numbers of fresh Meadow Browns during my visits to the Dorset coast in late August / early September, long after they have finished for the year back home in the midlands, although I have seen the odd individual locally in September.

Jeremy Thomas states in 'The Butterflies of Britain & Ireland' that the emergence of Meadow Browns is greatly prolonged on warm southern chalk downs where they continue to emerge throughout September and it is not unusual to see fresh females in mid-October.

He also states that there is no evidence that individuals aestivate...they simple emerge gradually over a longer period on English Chalk.

Cheers,

Neil.

I saw 6 Meadow Browns on my Brentwood transect yesterday and at least 2 were males. As Neil has researched, Meadow Brown larvae develop slowly and the emergence is protracted.

Neil Freeman wrote:This has come up before. I see good numbers of fresh Meadow Browns during my visits to the Dorset coast in late August / early September, long after they have finished for the year back home in the midlands, although I have seen the odd individual locally in September.

Jeremy Thomas states in 'The Butterflies of Britain & Ireland' that the emergence of Meadow Browns is greatly prolonged on warm southern chalk downs where they continue to emerge throughout September and it is not unusual to see fresh females in mid-October.

He also states that there is no evidence that individuals aestivate...they simple emerge gradually over a longer period on English Chalk.

Cheers,

Neil.

Thanks Neil.

I have a copy of the book and read Jeremy Thomas' account of the species before I responded . The article on the website which I outlined is dated Nov 2014 so probably post-dates Thomas' latest edition of the book. I still think Jeremy is right but it is certainly an area worth exploring further because he himself quotes '... by no means unusual to see fresh females in mid-October. Why this occurs is unknown.' as you also noted.

ATB

Peter

Neil Freeman wrote:This has come up before. I see good numbers of fresh Meadow Browns during my visits to the Dorset coast in late August / early September, long after they have finished for the year back home in the midlands, although I have seen the odd individual locally in September.

Jeremy Thomas states in 'The Butterflies of Britain & Ireland' that the emergence of Meadow Browns is greatly prolonged on warm southern chalk downs where they continue to emerge throughout September and it is not unusual to see fresh females in mid-October.

He also states that there is no evidence that individuals aestivate...they simple emerge gradually over a longer period on English Chalk.

Thanks for that reminder, Neil. Clearly, if males are being seen in numbers alongside females then the idea the latter aestivate holds less value.

Essex Bertie wrote:I saw 6 Meadow Browns on my Brentwood transect yesterday and at least 2 were males. As Neil has researched, Meadow Brown larvae develop slowly and the emergence is protracted.

Thanks Bertie. We'll see how the season progresses

ATB

Peter

Read this discussion with interest, as I've been doing Adonis Blue surveys in Dorset this month, and have seen 5 mating pairs of Meadow Brown since August 14th. I don't encounter these that often even in peak season, so was quite surprised by this, and have been wondering if this was a sign of delayed emergence caused by aestivation. To add a bit of weight to this, on Monday (27/08), I found a freshly emerged female at White Horse Hill (Nr Osmington), she was still drying her wings, with the pupal case underneath in a tussock underneath.

I'll post some pictures in the next couple of days when I get time.

Cheers,

Will