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The caterpillar like larval stage of two species of sawfly can completely defoliate Geum in spring and summer.
Geum sawfly (Claremontia waldheimii) on Geum
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.
There are two species of geum sawflies they have pale green larva, with small white spines. The larvae reach 15 mm in length that eat the leaves of Geum plants in the spring and summer. The adult insects are about 6 mm long and mainly black.
Geum sawfly larvae initially feed concealed between the folds of unexpanded leaves. As they grow they cause large irregular holes and damage can occur very quickly and defoliation can be extensive. Keep vigilant for early signs;
Geums can cope with some damage and low numbers of larvae and light damage can be tolerated.
Regularly inspect plants during the growing season and remove larvae from leaves.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
The larvae of geum sawflies (Claremontia waldheimii and Monophadnoides rubi) can cause extensive defoliation of cultivated and wild Geum species.
There is one generation a year with larvae active during late May and June. They initially they feed concealed between the folds of unexpanded leaves. The larvae of both species are pale green with rows of bifurcated whitish spines on the dorsal surface. When fully fed in late June they go into the soil where they spin silk cocoons, where they overwinter. The adults are 5-6mm in length, black in colour and emerge between late April and early June.
Chemical labels explained
Chemicals: using a sprayer
Chemicals: using safely and effectively
Rose large sawfly
Rose leaf-rolling sawfly
Rose slug sawfly or slugworm
Social pear sawfly
Solomon’s seal sawfly
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