Burnet moths in Cornwall
by John Worth
In the Victoria County History published in 1906 the Five-spot burnet
is described as very local whilst the Six-spot Burnet is described as
common throughout Cornwall. A century later and a similar situation exists
today with the five-spot's restricted distribution and the six-spot relatively
common especially along parts of the coasts. The Six-spot has the wider
distribution within the UK ranging from the Isles of Scilly to the Outer
Hebrides. The Five-spot has two subspecies in Britain, each with a distinct
ecology; ssp. palustrella is found on chalk downs and limestone
hills in southern England whilst it is ssp. decreta which is found
in Cornwall.
Decreta is confined to marshes, wet moorland, damp meadows
and occasionally to comparatively dry cliffs. Sites include Marazion Marsh,
Goss Moor and Breney Common. It is an indicator species of relatively
undamaged wetlands (W. G. Tremewan, 1985).
The distribution of the six-spot is no doubt incomplete
because many small colonies probably go unnoticed or unrecorded. For example,
a small colony at Roskilly, near Mousehole exists in a narrow area below
the road and coast path, but within the splash zone. An area where comparatively
few people let alone moth recorders visit.
Both species fly during the day and the graph is constructed from data
provided by recorders and shows the flight periods in Cornwall.
Both species broadcast their eggs near the foodplants. In the case of
the Five-spot the foodplant is greater bird's-foot trefoil (Lotus pedunculatus)
and for the Six-spot it is usually the common bird's-foot trefoil (L.
corniculatus), although it has been recorded on greater at the Lizard.
In Cornwall both species pupate in a cocoon, usually exposed on stems
of grasses, etc. Some guidebooks state that the Five-spot cocoon is concealed
amongst grass and other herbage but this refers to the subspecies palustrella.
Reference
Tremewan, W.T. 1985. Zygaenidae. In: Heath, J. and Maitland Emmet, A.
(eds.) The Moths and Butterflies of Great Britain and Ireland. Vol. 2.
Colchester: Harley Books.
Images can be seen at ukmoths:
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