can you identify the culprit that shreds the leaves on this plant & advise a remedy
Thank you for contacting the Toronto Master Gardeners.
Some common pests of Solomon’s Seal are slugs, snails, and Solomon’s Seal sawfly and these could be the cause of the leaf damage. This last insect, phymatocera aterrima, could very well be your main villain as it has a habit of eating elongate strips out of the leaves. It is actually its larvae caterpillars that do the most damage. They are greyish white with black heads and can be found on the undersides of the leaves, mostly after the plant has finished flowering. Hand picking these little critters off and dropping them in a container of soapy water is your best bet. Alternatively, you can spray the larvae with Insecticidal soap which is available from your local garden centre. Make sure to read the label and follow directions.
Once fully fed the larvae go into the soil where they overwinter and pupate in the following spring. By cultivating the soil exposes them to freezing weather and birds that feed on them. Cultivate the soil several times over the winter months, taking care not to damage the roots of dormant plants.
You may be interested in the following article: https://wimastergardener.org/article/sawflies/