Kildare Wildlife Watch: The metamorphosis of the pale tussock moth

With the Irish Peatland Conservation Council

Kildare Wildlife Watch: The metamorphosis of the pale tussock moth

The pale tussock moth caterpillar. Picture: Pat McCool

I hope you have enjoyed the Christmas break, as we relax and wait to welcome the New Year. I was delighted to receive this week’s species from Pat McCool who observed the various lifecycle stages of the pale tussock moth during metamorphosis earlier this year.

Metamorphosis is the biological process of change when an animal, after birth and during its growth, completely changes its body structure.

This week I am focusing on the pale tussock moth (dosóg éadrom leamhan as Gaeilge) which completely changes its body structure from a caterpillar to the adult moth.

I do believe I have shared this species with you before — however I only had a picture of the adult moth to share with you, and according to my records that was back in 2016 when I photographed the adult on a wall of a GAA club!

This adult moth lays tiny yellow/brown eggs on the leaves of their food plant throughout June; and between July and October each year the brightly coloured caterpillars can be seen.

Their preferred food plants include hawthorn, blackthorn, birches, oak and hazel trees.

The caterpillars are greenish or yellow with four distinct tufts of yellow hair. It is suggested that these brightly coloured tufts of hair help to protect the moth from predation by birds.

Pale tussock moths were once commonly referred to as ‘hop dogs’ as they were common moths found among growing crops. Today this moth is not as common in crop fields due to the use of pesticides.

At this time of year, the caterpillar is overwintering in its cocoon waiting until the arrival of spring when the adults will emerge.

The adult moth’s forewings are pale grey in colour with darker grey bands visible and these markings help to camouflage itself in the bark of trees.

The adult pale tussock moths do not feed. You can tell the difference between a male and female adult moth as the males often have feathery antennae to help locate the female.

From my colleagues and I at the Bog of Allen Nature Centre, I wish you all a peaceful New Year.

If you would like help identifying or to learn more about a wildlife species contact me via e-mail

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