The southern small white is heading our way from Europe, says Suffolk’s butterfly recorder.
While the UK borders may soon be less open to those coming from Europe, there is one visitor from the continent that is eagerly awaited by naturalists in Britain.
Suffolk butterfly recorder Bill Stone has been keeping tabs on the southern small white butterfly over the past decade, closely monitoring reports from European experts who have charted the insect’s march northwards towards Blighty.
Debut
Traditionally found in southern European countries, such as Southern France, Spain, Portugal and Italy, and as far south and east as northern Africa, Turkey and Syria, the southern small white has been increasing its range northwards by over 100kms a year, and last year reached the Netherlands and Belgium.
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Mr Stone believes it is only a matter of time before it reaches the UK. Depending on the weather conditions and the success of its breeding there is a possibility it could make it across the Channel by the autumn of this year. Failing that, there’s a good chance 2020 will be the year for it to make its debut on UK shores - with Suffolk, because of its proximity to these European neighbours, potentially being the first place it will land.
Mr Stone describes the southern small white butterfly as ‘noticeably smaller’ than the small white butterfly which is familiar to British lepidopterists.
“In the later broods, it is extremely well-marked with bolder spots - it is whiter on the upper part and on the lower wing is a creamy grey,” he added.
Consolidation
The southern small white is multi-brooded, meaning the female will produce a number of sets of eggs during the season. Typically, it is after the fourth brood has matured that much of the geographical expansion takes place but Mr Stone said the butterfly didn’t make the land gains expected last year because of the extreme weather we saw.
“It didn’t go as far as we thought it would - the hot weather and the drought affected the food plants of the caterpillars. Last year it consolidated its numbers in the locations where it has already been.
“There is the potential that it could make it to Suffolk this year - if it has a good year, the latter broods might make it to the coast. But it is more likely it will make it across next year.”
Robust
Before the southern small white gets to the UK, there is one big obstacle in its way - the English Channel - and it is unclear how it might deal with this large expanse of water. However, Mr Stone says both the large white and small white butterflies are regular migrants and manage this crossing easily in suitable weather.
He says the journey should hold no fears for the butterfly known to be a robust and hardy insect able to exist in a variety of habitats and climates, including up to 2000 metres above sea level in the Atlas Mountains in Morocco.
Mr Stone says whenever the southern small white does make it to Suffolk, those likely to see it first will be those walking coastal paths or near gardens with Candy Tuft - a common garden plant that its caterpillar feeds on.
So, keep an eye out, especially towards the autumn, and if you think you see a southern small white try and take a photograph so it can be formally identified.
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