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In Victorian times the large tortoiseshell butterfly (Nymphalis polychloros) was regarded as being a common species in the United Kingdom, but that is certainly not the case today. Sightings in Britain are extremely rare, with only around 200 logged over the past fifty years, these almost certainly being specimens that were blown over the English Channel from continental Europe.
One possible cause for the decline is the virtual extinction of the English elm – the result of Dutch Elm Disease – and this was one of the large tortoiseshell’s regular food plants.
If the large tortoiseshell is rare in Britain, that is not the case in other parts of the world. It is quite common in continental Europe and it is also found further south and east – in north Africa, Asia Minor, and even as far east as the foothills of the Himalayas of central Asia.
There are a number of large tortoiseshell subspecies which have developed as a result of different temperature ranges at various altitudes. For example, although Nymphalis polychloros is found from sea level up to 1500 metres, the subspecies Nymphalis polychloros erythromelas can be seen at up to 1800 metres in mountainous areas of north Africa.
<a href="https://en.wikipedia.org/wiki/Nymphalis#/media/File:Nymphalis_polychloros.jpg" target="_blank" rel="noopener">Source</a>
Appearance
The large tortoiseshell has a wingspan of 50 to 63 mm (2 to 2.5 inches). It has orange-brown forewings with black markings that are almost circular in the centre of the forewings but elongated at the leading edges.
The hindwings are also orange-brown and do not have as many darker markings as the forewings.
The wing margins are scalloped, with a row of small blue crescents on the hindwings.
The underwings are darker towards the base with a blue-grey band towards the margins.
There are no noticeable differences in appearance as between males and females.
Behaviour
Female large tortoiseshell butterflies lay their eggs, which are barrel-shaped and red-brown, soon after they emerge from hibernation. The caterpillars hatch after about three weeks and stay in groups on their food plants, which are poplar, willow, elm and fruit trees.
The caterpillars move apart as they prepare to pupate, which they do underneath the leaves of their food plant.
The pupal stage takes two to three weeks after which the imagos take flight from June or July before hibernating through the winter.
How do you distinguish a moth from a butterfly?
Rex Trulove is the guy to ask on this one. There is no simple answer because there is no characteristic that is held by 100% of moths and 0% of butterflies, and vice versa. However, the antennae are probably the best indicator, in that all European butterflies have a “club” at the end and nearly all moths do not. But even here there are exceptions – some moth species do!
I love the design of their wings. I used to get these confused with Red Admiral butterflies but although the colours are similar the pattern is different.
Very interesting.
You mentioned the scarcity of the English Elm as the reason for their rarity in Britain. Are there sufficient English Elms on continental Europe or does the butterfly use a different tree there?
That`s a good question. I think it`s probably the case that generations of butterflies in a particular locality use the same food plants and find it difficult to adapt to a new one. If the continental generations used – say – willow, they would survive, even though the same willow species grew in the UK.
yea!
Nice!
Beautiful.
At least the butterflies adapted and learned how to live with mankind somewhere on the planet, if not in the United Kingdom. Even creatures know when it’s time to pull up roots and move on to start another life. LOL.
In the vicinity of my house, long ago, I often see it at night. Now it’s never seen it at all. We call it a night butterfly, a nickname that is often used to soften the mention of those who sell love at night.
What a beautiful butterfly!
It looks very similar to the small tortoiseshell, which is seen much more commonly in the UK.