www.ukbutterflies.co.uk

With several photos of small copper aberrations recently posted on the site, it would be interesting if the experts could offer an explanation as to why aberrations occur. Are they just genetic freaks or are other factors at work?

I'm not an expert, but in very simple terms, the 2 factors are (I believe):

1. Genetics.
2. Environment.

E.B.Ford's book, "Butterflies", goes into these in some detail and makes a wonderful read!

Genetic variation can itself be broken down into several categories that I won't go into here. But a good example is the occurrence of the ab. arete in the Ringlet, where the rings are all but missing. Offspring can be guaranteed to be ab. arete if you choose the right parents!

Environmental variation is normally caused through extremes of temperature. For example, ab. semi-ichnusoides in the Small Tortoiseshell is caused by the temperature in the pupal state being excessively high. Conversely, ab. nigrina in the White Admiral is caused by the temperature in the pupal state being too low (for example, the larva may have pupated near the ground which then forms a "frost pocket").

Cheers,

- Pete