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The marbled white is a brown; that is to say that it is a member of the family Nymphalidae to which many of our brown coloured butterflies belong. To look at, of course, it bears little resemblance colourwise to its cousins being very definitely an attractive patchwork of black and white. This pattern marks them out from all other British species and they should not be confused with anything else. This is a butterfly of flower rich downland and grassy places and thrives in dry, hot conditions. They seem to have a particular liking for purple/mauve flowers and adore knapweeds and thistles and so chalk or limestone grassland is particularly suitable for them but they do also occur in woodlands, along railway lines and even roadsides and hedgerows. Where they do occur their population can often far outnumber other species.
The marbled white is single brooded and flies from mid-June to mid-August. Our Dorset records suggest emergence here is in week 24, right in the middle of June, just as the textbooks say, and reports are continuous through until week 30 at the end of July. After a gap in weeks 31 to 33 there are then two reports in week 34 and week 35, mid August. Strangely, we have one report from week 45 in November 2017!
There are records from 61 sites across Dorset with Durlston, Lulworth and Badbury Rings seemingly good places to see them. The distribution map, though, puts this in to context showing a definite preference in Dorset for the limestone of the Purbeck coast and Portland and the central chalk ridge that runs from south west to north east Dorset. It is not exclusive to calcareous soils but almost all sites on this geological foundation do seem to have colonies of them.
Contributed by: Peter Orchard