The return of the Large Tortoiseshell butterfly to the Isle of Wight

They have in the past had short spells of abundance that were then followed by longer periods of scarcity and there would appear to be no definable reason for this.

The Islander, Herbert F. Poole, writing in 1909, said that the butterfly was 'not common but distributed all over the Island'.

Since then it has declined with only sporadic sightings some of which in more recent times were from butterflies reared from Continental stock and released here in an attempt to re-instate the species.

This is a woodland butterfly with the adults on the wing in June, July and occasionally August. It then hibernates in sheds or holes in old trees and emerges in February.

By late March or early April they have mated and the females then fly through the treetops looking for the right ones on which to lay their large clusters of eggs.

Elm, sallow and willow are preferred and it is significant that the very obvious silken webs that the caterpillars live in have not been found and recorded anywhere in recent years.

It may be, of course, that they have just been missed as nobody has been specifically looking for them.

Modern authors when writing about the large tortoiseshell tend to dismiss any sightings as being releases and not genuinely wild but this is certainly a mistake.

Looking at the past 25 years there have been consistent reports of the butterfly being seen in southern coastal areas of the Isle of Wight and even observed from a boat heading for land, Bonchurch to be precise in 2005.

These sightings usually coincide with large movements of other insects such as hoverflies as well as butterflies that then move on inland.

Seaside gardens have attracted a number over the years such as one seen in a garden in Wheelers Bay that stayed for a while before hibernating and emerging to be seen briefly the following February in 2007.

In fact, there are sightings most years of incoming migrants with unknown numbers that are missed.

This year, 2026, there have been numerous records of possible hibernating large tortoiseshells emerging in woodland at Newtown and Parkhurst early in the year so it will be interesting to see if there are corresponding sightings of the adult butterfly in June or July giving an indication that they have perhaps bred here.

Let’s hope so.