Sawflies are a group of insects suborder (Symphyta) of the Hymenoptera (bees, ants and wasps). There are about 500 species of

Sawfly are small winged insects, related to bees, wasps and ants. Their caterpillar-like larvae feed on the leaves or fruits of certain plants, including apples, gooseberries and Solomen’s seal.

Geum sawfly larvae initially feed concealed between the folds of unexpanded leaves. As they grow they consume large irregular holes and damage can occur very quickly and defoliation can be extensive. Signs of geum sawflies include;

• Pale green caterpillar-like larvae with small whitish spikes up to 15 mm long
• Leaves can be reduced to a network of the larger leaf veins, affecting the appearance and vigour of  plants
• Affected plant often recover with no long term effects

Check geums frequently from spring onwards so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by using the methods in the non-pesticide section below. Pesticide treatments are likely to kill natural enemies and are only likely to be successful if the entire plant can be reached.

Geums can cope with low numbers of larvae and damage can usually be tolerated and the presence of these insects treated as part of the biodiversity a healthy garden supports.

Non-pesticide

• Where possible treat this sawfly as part of the biodiversity a healthy garden can support, plants usually recover from defoliation
• Encourage predators and other natural enemies of sawfly in the garden, such as birds and ground beetles.
• Check plants regularly in May and June for the presence of larvae and remove by hand where practical

Pesticides

• If numbers of larvae are too high for hand picking, control may be achieved by spraying with pesticides. Spraying at dusk is likely to be more effective
• Organic contact insecticides containing natural pyrethrum (e.g. Bug Clear Ultra 2, Neudorff Bug Free Bug and Larvae Killer) have a largely physical mode of action. These are broad spectrum so will kill a wide range of insects. Several applications of these short persistence products may be necessary to give good control. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults
• Further information about the use of pesticides available for management of sawfly is available on the pesticides for gardeners leaflet

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Pesticides for gardeners (pdf document outlining pesticides available to home gardeners)

The larvae of geum sawflies (Claremontia waldheimii and Monophadnoides rubi) feed on the foliage of cultivated and wild Geum species.

There is one generation a year with larvae active during late May and June. They initially feed concealed between the folds of unexpanded leaves. The larvae of both species are pale green with rows of bifurcated (divided into two) whitish spines on the dorsal surface. When fully grown in late June they go into the soil where they spin silk cocoons, where they overwinter. The adults are 5-6 mm in length, black in colour and emerge between late April and early June.