Pestwatch: Solomon’s Seal Sawfly
If you grow any variety of Polygonatum, common name Solomon’s seal, you may well find a bunch of these little critters hanging around your plants round about now:
This black insect is less than a centimetre long and looks fairly innocuous, but its offspring, a whitish-grey grub, can completely defoliate a plant by mid summer leaving it weakened for the following year, not to mention very unsightly in the meantime!
Controlling the adult insects isn’t really an option – I have been known to swat a few if I see them, though! – so the best thing to do is look out for early signs of larval activity (holes being eaten in the leaves) then search the undersides of leaves and remove the offenders.
If control by hand is impractical, plants can be sprayed with chemicals such as Westland Resolva Bug Killer (there are other recommendations on the RHS website).