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2. Dusky Thorn, August Thorn and September Thorn
All three species have two cross-lines on the forewing as in most thorns.
The Dusky Thorn has the area between the outer cross-line and the outer edge of the
wing grey. Some August Thorns also have this area grey though most are uniform in
colour. The September Thorn is uniform in colour.
The main distinguishing character is the outer of the two cross-lines on the forewing
- in particular the angle at which the outer cross-line contacts the trailing edge
of the forewing.
1. Canary-shouldered thorn
Size, markings and flight time are similar to other thorns, but the bright Canary
yellow head and thorax are very distinctive.
Dusky Thorn - the outer cross-line curves round to meet or nearly meet the inner
cross-line at the trailing edge of the forewing.
August Thorn 1. the outer cross-line curves towards the inner cross-line at the trailing
edge but not so far as in Dusky Thorn.
2. the outer cross-line also has a kink where it meets the leading edge of the forewing.
September Thorn - the outer cross-line curves towards the inner cross-line and then
straightens out to meet the trailing edge at right-angles.
There are quite a few Thorn moths - the first four have flight periods which overlap,
are of about the same size with similar markings.
Purple Thorn
March-May, July-August.
Rests with wings in a curve
Early Thorn
Feb-May, July-September
Rests with wings flat together
Feathered Thorn
September-December
Rests with wings flat apart
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