Geum sawfly, or Claremontia waldheimii, is an insect closely related to wasps but lacks the characteristic 'wasp waist'. A female will lay her eggs beneath the leaves of geum plants, giving rise to one generation each year. From these eggs hatch small pale green larvae with white hairs running laterally down the body, similar to caterpillars, which begin to feast on Geum leaves in spring and through to the summer. It's the larvae that are most damaging to garden plants, who feed primarily on the leaves. Geums can tolerate some damage if these larvae are in low numbers.
Larvae can demolish the leaves of Geum plants when in high abundance.
Adult sawfly feed mainly on pollen and nectar so can be considered a beneficial pollinator for your garden.
Active Spring through to Autumn. Claremontia waldheimii has a small black body, reaching 6mm in length. They emerge between early April to late June. The larval stage of Geum sawfly resembles a caterpillar. They are pale green with two rows of distinctive white two-pronged spikes, running laterally down the body. They are relatively small, reaching only 1.5cm.
Pale green caterpillars with white spikes may be evident on the leaves of Geum plants. They can deplete whole leaves, leaving behind a skeleton of veins. This can affect short-term vigour and make plants unattractive.
Parts of Europe including the UK.
These larvae can be removed by hand and disposed of. Alternatively, put these on a bird table in your garden for the birds to feast on!
If infestations are too heavy, pesticides can be the next alternative. Please speak to your local garden centre for advice on what treatment will work best for your garden. Flowering plants should never be sprayed due to the risk they pose to pollinating insects. Bottle labels should be read carefully before the application of pesticides.
The larvae of this species feed primarily on plants belonging to the Geum genera.