Rivulet | Geometridae |
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Perizoma affinitata (Stephens, 1831)
Description: Wingspan 24-30mm. Adults have brownish forewings with a distinctive white band. There is a single indention on the inner margin of the band.
Similar Species: Closely resembles the Small Rivulet P. alchemillata which is smaller and has a double indention.
Key Identification Features:
Sets: | ![]() |
Flight Period: Beginning of June to early August.
Status: Widely distributed but local, with most of the recent records from Down. Recorded recently on the North Antrim coast at Portrush, which is the only recent record north of Lough Neagh, although old records exist for Magilligan and Banagher Glen, Londonderry. It has also been taken at Aghalee, Antrim, and the Lagan Meadows and Belfast, Down in the late 1990s.
Ecology: A woodland species that is much less frequently encountered than the closely related Small Rivulet P. alchemillata. The lack of records in the west is probably due to the scarcity of its foodplant. Adults are attracted to light in very small numbers. The larvae can be found from July to September in the seed capsules of Red Campion Silene dioica. It overwinters as a pupa.
World Distribution: Northern and Central Europe.
Bradley & Fletcher number: 1802 Agassiz number: 70.132
Additional information:
Caterpillar: | ![]() |
Thompson, R. S. & Nelson, B., 2003 (Oct 2). [In] The Butterflies and Moths of Northern Ireland http://www.ulstermuseum.org.uk/lepidoptera/species.asp?item=5882 |
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