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The caterpillar like larvae of large rose sawflies eat the leaves of wild and cultivated roses.
Larvae of large rose sawfly. Image: RHS, Horticultural Science
Sawflies are in the same group of insects as bees, ants and wasps (the Hymenoptera). They have caterpillar like larvae that feed on plants the adults are winged insects that can appear fly-like.
Large rose sawflies have pale spotted black, green and yellow larvae that eat the leaves of roses, sometimes causing severe defoliation. The adults have yellow abdomens with mainly black thorax and heads.
Roses can also be attacked by other sawflies such as the rose leaf-rolling sawfly and rose slug sawfly or slugworm.
You may see the following symptoms:
Healthy roses can cope with some defoliation and the presence of some larvae can be tolerated.
The larvae can be removed by hand. If eggs are present in the stems these can also be destroyed.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
In Britain there are two species of large rose sawfly: Arge pagana and A. ochropus. The adult insects of both species have yellow abdomens with the legs, thorax and heads being mostly black. Arge pagana is the more common species.
Rows of eggs are inserted into soft young rose shoots and female sawflies are sometimes seen dangling from such stems, attached only by their saw-like egg-laying organs.
After hatching, the larvae feed together in family groups. They are pale green with black spots and yellow blotches, and are up to 25mm (about 1in) long. When fully fed, they go into the soil to pupate.
The large rose sawfly (Arge pagana) will produce two (sometimes three) generations from May to October. Arge ochropus usually has a single generation in early summer, but sometimes there is a second generation in late summer.
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Chemicals: using a sprayer
Chemicals: using safely and effectively
Rose leaf-rolling sawfly
Rose root aphid
Rose slug sawfly or slugworm
Social pear sawfly
Solomon's seal sawfly
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