Clifden Nonpareil

Catocala fraxini

Clifden Nonpareil, Blue Underwing, Blue Underwing, Underwing Moth

profile iconCatocala fraxini 01a (HS)
by Harald Süpfle (CC BY-SA 3.0)
1 of 4
A close up of a Clifden Nonpareil Catocala fraxini moth on some tree bark
profile iconCatocala fraxini 01a (HS)
by Harald Süpfle (CC BY-SA 3.0)
1 of 4
Clifden Nonpareil is a beautiful and rare moth native to the British Isles. It has been absent for many years until recently, where it's now been sighted in southern England on several occasions. Catocala fraxini is also sometimes called a Blue Underwing, namely after the contrasting blue bands on the hindwings, which are only displayed when the moth extends its forewings at rest. These moths favour broadleaved woodland, with the highest periods of activity peaking in the evenings. Nonetheless, it's still possible to see these beautiful moths resting on garden trees from late August through to early October, if you're lucky enough! These insects are typically more frequent in southern European localities, hence why they are rarely seen in northern Europe! Sometimes, they can be attracted to the garden using fermenting fruits.
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A beautiful and rare moth that's one of the the largest of it's kind!
This species of underwing is seldom seen, but they will occasionally visit gardens.


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.











Widespread across Europe but low in numbers.

Biological treatment

These moths are rare and cause no damage to garden plants.


These insects will feed on plants of the Populus genus as caterpillars switching to fruit-bearing plants as adults!
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