This large and striking butterfly is rather localised in its Irish distribution but where it exists it is particularly evident at this time of year when mating and egg-laying are taking place.
Flower-rich woodland margins and glades are its natural habitat, though it sometimes turns up in gardens. Males are a luminous yellow and females are pale green.
When they fold their wings, both sexes reveal veined under-wings that camouflage them to look remarkably like a leaf.
They produce one brood a year and hibernate as winged adults, hanging themselves up in holly or ivy in September and reappearing as early as March.
They tend to fly only when there’s strong sunlight and have a curious habit of retiring for the night by 3am and not getting up before about 9am.
The food plants of the caterpillars are two related but rather uncommon small trees — common buckthorn and alder buckthorn. The trees, and the butterflies, are only found in parts of the Midlands and west.
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