Sunday, 15 August 2010

Eggar question

As Northern Eggars have a two year life-cycle, does that mean you only see them on the wing in alternate years?

They were on the wing during the Twite survey on Midgely Moor last year (May/June?).
All postings on the blog this year relate to cats, with postings relating to adults all being from June 09.
I haven't seen any this year, but I haven't always been around suitable habitat.

3 comments:

Paul Talbot..aka Moffman said...

First winter spent hibernating as a larvae and second winter as a pupa. Obviously there may be exceptions and the two year cycle might vary from area to area, but basically once every two years as adults.

TheBaldIbis said...

So do all the populations pass their life cycles in synchrony resulting in adults only being seen in alternate years?

Paul Talbot..aka Moffman said...

Obviously there may be exceptions and the two year cycle might vary from area to area, but basically once every two years as adults.....

As I stated above this is the life cycle in the north due most probably one would assume to climate. Should the north of England start warming then this might well change to a one year cycle. With lepidoptera one cannot be dogmatic about times adults appear as there are freak emergences such as the Common Quaker I once recorded in December (was it late or early ?) Spring Usher is now emerging and finishing as an adult around 30 days earlier than it did historically (see Roy Levertons article which I think Andy has a copy of ?). Collins (the former Halifax recorder) used to rear Emperor Moth cats to release every two years and in alternate years he put down Pupa to try and raise the population (lost due to Moor Burning for Grouse).