Large Rose Sawfly - Arge pagana
Arge pagana is entirely black, except for the abdomen which is yellowish orange. Because of the dark, blackish wings, which are kept over the abdomen, the orange colour may not always be clearly visible. The legs are mainly black as well, with some orange on the hind leg femur. Like all species in the Arge genus, the antennae have only 3 or 4 segments, with the end segment being very long.
Larvae of Arge ochropus and Arge pagana are tricky to separate, especially from photos. The best feature to check are the fine hairs on the head, which are dark in ochropus and pale in pagana. The black marking on the last dorsal segment can also be useful – this is a simple spot in pagana but more-or-less indented with a pale middle in ochropus. In the field the best way is to look for the egg scars on the main stem near where the larvae are feeding – two parallel rows in pagana and just a single row in ochropus.
Hedgerows and gardens, especially where rose species are present.
March to June
Like all sawflies, female Large Rose Sawflies are in possession of a little saw. With it they make parallel cuts in the fresh shoots of the host plant. In the cut a bunch of eggs is deposited. The larvae hatch quite quickly and move in a group to the freshly emerged leaves. The young larvae (yellow with black spots) stay together for quite some time, capable of eating the entire shoot. Older larvae lead a more single life and eat from older leaves as well.
The Large Rose Sawfly is a common species all over Britain, although most records come from the south of England.
Common in Leicestershire and Rutland.
Leicestershire & Rutland Map
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