Fox moth caterpillar and moth

Female Fox moth (Macrothylacia rubi) © 2007 Steve Ogden

Recently emerged male Fox Moth © 2008 Steve Ogden

Fox Moth male (Macrothylacia rubi) attracted to light in Cornish garden © 2018 Steve OgdenThe Fox Moth is found throughout much of the British Isles but is less common in central and eastern England.

In Cornwall it is most commonly found on moorlands, heathland and coastal areas.

The moths fly in a single generation between May and June when the nocturnal females are attracted to light.

The daytime flying males can be seen during sunny days flying quickly over low lying vegetation seeking out newly emerged females.

Male Fox moth combed antennae © 2009 Steve OgdenMale Fox moth  (Macrothylacia rubi) © 2008 Steve Ogden

Fox Moth male (Macrothylacia rubi) attracted to light © 2018 Steve OgdenFox Moth male (Macrothylacia rubi) © 2018 Steve Ogden

Identification of the Fox moth

The smaller male Fox Moth has a wing span of approximately 50mm, ruddy brown forewings, a heavily combed antennae and flies mainly during the day.
On occasions a male, such as the one featured above, is attracted to light at night.

The larger female has a wing span of up to 65mm, more subdued greyish brown forewings and hindwings, an uncombed antennae and flies at night.

Both male and female have two pale cross lines.

Moth galleries

Butterfly galleries

Fox Moth (Macrothylacia rubi) over wintered final instar caterpillar © 2008 Steve Ogden

Fox Moth caterpillar

The fully grown caterpillar is up to 70mm long, very hairy, dark brown with an orangey stripe extending down the length of its body.

During its early development stages it is a dark brown with distinctive orangey/yellow bands.

The caterpillars are commonly found sunning themselves on paths and on top of low vegetation.

Other hairy caterpillars

For help with caterpillar identification

British moth caterpillar Gallery

Fox Moth life cycle

Fox Moth eggs (Macrothylacia rubi) on bramble © 2015 Steve OgdenFox Moth caterpillars hatching from eggs laid on bramble © 2015 Steve Ogden

The adult Fox moths fly in a single generation in May and June.

The males fly during the daytime when they use their combed antennae to smell the pheromones given off by a recently emerged, unmated female.

Flying low over vegetation the males fast, jagged flight can often be seen on warm sunny afternoon. Once a recently emerged female has been located in the vegetation the male will mate with her before moving on to find another unmated female.

The female lays batches of grey eggs at night on the stems of grasses and the leaves of the larval food plant such as brambles and heathers.
Fox Moth caterpillars hatching from eggs laid on bramble © 2015 Steve Ogden3 day old Fox moth caterpillar  © 2015 Steve Ogden

The caterpillars hatch within three weeks and feed on a variety of food plants including Heathers, Bramble, Sallows, Bilberry, Salad Burnet and Meadowsweet.

The fully grown caterpillars are often seen basking in the sun on paths and low vegetation prior to over wintering in leaf litter and loose soil.

They emerge from over wintering in early spring when they can again be seen basking in the sun.

They then pupate for a month within a cocoon low down amongst the vegetation.

14 day old fox moth caterpillar © 2015 Steve OgdenFox moth caterpillar (Macrothylacia rubi)  late summer instar © 2009 Steve Ogden

Fox moth caterpillar (Macrothylacia rubi)  late summer instar © 2009 Steve OgdenFox Moth pupa inside cocoon © 2015 Steve Ogden

Fox Moth pre over wintering caterpillar © 2009 Steve Ogden

Rearing the Fox moth caterpillar

Clusters of grey eggs can be found on the larval food plants but many of the larvae collected in the wild are often parasatised by wasps.

As with many caterpillars that overwinter rearing them through to the following Spring is not always successful.

The best chance of success is to keep the over wintering caterpillar outside in an environment that matches closely their natural one.

British moth caterpillar Gallery

American caterpillar galleries

For help with caterpillar identifications

Recommended reference books

The Colour Identification Guide to Caterpillars of the British Isles – Jim Porter.
Field Guide to the Moths of Great Britain and Ireland – Waring, Townsend and Lewington.
Moths of the British Isles – Bernard Skinnner.
Provisional Atlas of UK’s Larger moths -Randle, Fox and Parsons.