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Swallow Prominent Pheosia tremula

Picture of Pheosia gnoma and Pheosia tremula

The Swallow Prominent and the Lesser Swallow Prominent are almost identical. Yet it is easy to tell the two species apart. Just look at the white wedges marked in the picture above. In the Lesser Swallow Prominent this is a triangle, in the Swallow Prominent this is a much longer and thinner line.

Measuring 22 to 28 mm and reaching a wingspan up to 55 mm, the Swallow Prominent is slightly larger than the Lesser Swallow Prominent, but there is a lot of overlap. It is on the wing from mid-April to the beginning of September and is double brooded. The caterpillars are up to 40 mm in length and extremely shiny. They are either light green, or light brown. The caterpillars feed on Sallow and Poplar and sometimes on Birch. The Swallow Prominent overwinters in the ground in the pupal stage. This is a fairly common species all over Britain. In the north however it is single brooded and on the wing from June to August only.