2nd brood Marsh Fritillaries?
Posted: Mon Sep 02, 2019 2:35 pm
Up until a few days ago, I had thought that the Marsh Fritillary was strictly single-brooded, with the larvae being obligate hibernators on entering the fourth instar. I also thought that it was univoltine, not just in the UK, but across Europe as a whole. All the books say so, or so I thought.
I was very surprised therefore when reports started coming through of a few adult Marsh Fritillaries on the wing in central Lincolnshire last Friday.
Today I went out to look for myself, and took the photographs below: E.aurinia - 2nd September 2019 - Lincolnshire Limewoods
A little more digging, and I found this in "La Vie des Papillons" by Lafranchis, Jutzeler, Guillosson, Kan & Kan :
"De rares chenilles grandissent plus vite et atteignent le derniere estade en fin d'été. Elles se nymphosent pour produire d'exceptionelles émergences d'imagos de seconde génération en Septembre."
(translation: Rare caterpillars grow more quickly and reach the final stage at the end of summer. They pupate to produce exceptional emergences of second generation adults in September.)
Is this a case of a 2nd generation in Lincolnshire this year?
There is an alternative possibility that the adults currently on the wing (and there are only a few so far) are the result of delayed larval development from earlier this year.
This particular colony has experienced a massive population explosion over the past two years, to such extent that many thousands of larvae left the main breeding area to move into surrounding woods this spring. Some successfully completed their development on honeysuckle; many hundreds perished. During the main flight period (early May-June-early July) many thousands of adults were on the wing, but at the same time it was possible to still find small, post-hibernation-sized larvae. At one point in early April, the Devil's-bit Scabious had been almost entirely stripped across large parts of the site, and at least one group of 4th instar larvae was found later in early summer, having apparently gone back into diapause. For several weeks in late June one could find pupae, adults, eggs, 1st, 2nd, 4th, 5th and 6th instar larvae simultaneously.
My question to the collective wisdom embodied within this group is this: does anyone have any experience of putative 2nd brood Marsh Fritillaries, either in the UK or in Europe? Does anyone have any comments or theories as to why in early September it is currently possible to find adult Marsh Fritillaries at nectar on the larval foodplant (photographs such as those above are a complete novelty to me! I would have previously deemed them fake...) here in central Lincs? Or indeed has anyone experienced 2nd broods of this species in captivity?
All theories and thoughts welcome!
I was very surprised therefore when reports started coming through of a few adult Marsh Fritillaries on the wing in central Lincolnshire last Friday.
Today I went out to look for myself, and took the photographs below: E.aurinia - 2nd September 2019 - Lincolnshire Limewoods
A little more digging, and I found this in "La Vie des Papillons" by Lafranchis, Jutzeler, Guillosson, Kan & Kan :
"De rares chenilles grandissent plus vite et atteignent le derniere estade en fin d'été. Elles se nymphosent pour produire d'exceptionelles émergences d'imagos de seconde génération en Septembre."
(translation: Rare caterpillars grow more quickly and reach the final stage at the end of summer. They pupate to produce exceptional emergences of second generation adults in September.)
Is this a case of a 2nd generation in Lincolnshire this year?
There is an alternative possibility that the adults currently on the wing (and there are only a few so far) are the result of delayed larval development from earlier this year.
This particular colony has experienced a massive population explosion over the past two years, to such extent that many thousands of larvae left the main breeding area to move into surrounding woods this spring. Some successfully completed their development on honeysuckle; many hundreds perished. During the main flight period (early May-June-early July) many thousands of adults were on the wing, but at the same time it was possible to still find small, post-hibernation-sized larvae. At one point in early April, the Devil's-bit Scabious had been almost entirely stripped across large parts of the site, and at least one group of 4th instar larvae was found later in early summer, having apparently gone back into diapause. For several weeks in late June one could find pupae, adults, eggs, 1st, 2nd, 4th, 5th and 6th instar larvae simultaneously.
My question to the collective wisdom embodied within this group is this: does anyone have any experience of putative 2nd brood Marsh Fritillaries, either in the UK or in Europe? Does anyone have any comments or theories as to why in early September it is currently possible to find adult Marsh Fritillaries at nectar on the larval foodplant (photographs such as those above are a complete novelty to me! I would have previously deemed them fake...) here in central Lincs? Or indeed has anyone experienced 2nd broods of this species in captivity?
All theories and thoughts welcome!