Friday, 18 July 2014

Oak Eggar

While surveying for Brown Hairstreak eggs near Weston-on-the-Green, Oxon on 29th October last year, I found a half-grown Oak Eggar larva hibernating on a blackthorn stem and it was taken home in an attempt to rear through.  I have a poor success rate with species that hibernate as partly-grown caterpillars but on this occasion things went to plan, the caterpillar survived and it began feeding again in the Spring (it was content to eat ivy as there were no blackthorn leaves available at that stage).  The fully-grown larva spun up its cocoon on 27th May and pupated, a handsome male emerging yesterday (17th July).  Wendy Wilson gave me a larger cocoon of the same species a couple of weeks ago for safe keeping while she went away on holiday, her larva having been found in the same way but at Otmoor, Oxon.  By co-incidence it also emerged yesterday and proved to be a female.  Oak Eggar is an uncommon moth in all three of our counties and I've only encountered an adult once before in Bucks, back in July 2009 when a female came to light in Bernwood Forest.  Like the Fox Moth and Emperor Moth, the males are day-flyers.   Dave Wilton

Oak Eggar larva, 29th October 2013

Oak Eggar larva, 1st May 2014

Oak Eggar male, 17th July 2014

Oak Eggar female, 17th July 2014


  1. Nice result, Dave - i brought a fully grown larva back from Dorset in June which spun a cocoon, but it was parasitised - inside the cocoon was another large cocoon, about the size of a Birch sawfly! So i still don't have a photo of an Oak eggar moth, but am intrigued to see what comes out of the other cocoon!

  2. Hi Dave, does this mean that Oak Eggar has now been added to your garden list??

  3. I'm afraid not!! The female did spend 24 hours outside in a flight cage and was "calling" for all of that time, but there was no sign of a wild male appearing. Sadly it is a species that will have to wait for another day, although it is not out of the question that it could join the garden list at some point in the future. In 2005 I found a caterpillar in the same way at a site only 5km from where I live.


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