I came across this striking hairy caterpillar as it crawled over a sea wall when I was on a visit to Llandudno, Wales. They do not feed on oak as the English name leads us to believe, but its cocoon looks much like an acorn. The hairs may cause skin irritation, which is the caterpillar’s defense mechanism. They can grow up to 80mm long.
The larva can take a year to grow in the south, and two years further norther where it is cooler. They feed quite rapidly and change appearance as they grow which can make them hard to identify compared to other Eggars. It feeds on a variety of plants, including heather and bramble.
© Pete Hillman April 2014, West Shore, Llandudno, Wales