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Clifden Nonpareil

Catocala fraxini

Clifden Nonpareil, Blue Underwing, Blue Underwing, Underwing Moth

A close up of a Clifden Nonpareil Catocala fraxini moth on some tree bark

Catocala fraxini 01a (HS)

by Harald Süpfle. CC BY-SA 3.0

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Clifden Nonpareil is a beautiful and rare moth native to the British Isles. Catocala fraxini is also called a Blue Underwing, after the blue bands on the hindwings. These are displayed when the moth extends its forewings while resting. They favour broadleaved woodland, with the highest periods of activity peaking in the evenings. These insects are typically more frequent in southern European localities. It's still possible to see these beautiful moths resting on garden trees from late August to early October (if you're lucky enough!). Sometimes they can be attracted to the garden using fermenting fruits.
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A beautiful and rare moth.
Its numbers have been in decline, but sightings still exist.


Adults: Underwing moths possess characteristic wing patterning that makes them easy to identify (Catocala). The forewings are a mottled grey, white and brown, resembling many other species. However, when the forewings become extended they reveal the distinctive black hindwings with vivid blue/ lilac stripes. Females: Mature female moths are always bigger than males. A Blue Underwing female can have a wingspan as large as 9.5cm. Females can sometimes be seen resting on walls, fences and tree trunks. The caterpillars can vary but generally resemble the patterning seen on the forewings of the adults. These are strongly associated with species within the Populus genus. They can vary anywhere between 4-9cm. Larvae: The caterpillars are greyish-blue and large in size (length: 7- 8cm) with 3 pairs of legs near the front of the body; 4 pairs of prolegs (unsegmented legs) towards the rear. Eggs: Description currently unavailable.


Caterpillars may be seen on the leaves of plants within the Populus genus. Won't cause severe damage to plants.











Europe, rare to the UK


Poplar Tree

Populus spp.


Populus tremula

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