I have only myself to blame – I have been away too much recently; the majority of the garden has been neglected due to clearing space for the workshop; and recently the heat has reduced my energy and enthusiasm. How do I know that I haven’t had my eye on the ball? Well you only have to look at the state of the Solomon’s Seal (Polygonatum) leaves above.
I had noticed something had been nibbling the leaves when I was potting up on the patio a couple of days ago. Today when I was watering I noticed that a second plant was being nibbled and then I noticed that the first plant had been almost completely defoliated.
In the recesses of my mind I knew this was caused by the Solomon’s Seal Sawfly, obvious really given the name. As I was watering I turned over the leaves on the lesser damaged plant and spotted a grey caterpillar, very tiny and thin, almost missable. So I dutifully sprayed all the stems with the hose to blast the caterpillars off. However, it occurred to me that the caterpillars would surely just crawl back. Having put the hose away I decided to investigate further and battled to the back of the border where the first defoliated plant was. The fact that I battled shows how out of control things are since I had planned to put a simple bark path round here last Spring; if I had done this I probably would have noticed the damage earlier.
Looking at the stems there were still some caterpillars and then I lifted a stem which was lying low and was horrified to see the mass of caterpillars below – it really turned my stomach!
What to do? I decided to cut both plants back to the ground and to put the stems, with caterpillars, in hot water. Then I will bag up the stems and put them out with the rubbish rather than adding to the compost bin or adding to green waste at the recycling centre.
Research says that the sawfly lays its eggs in the base of the stems in early Spring and this causes purplish brown scars on the stems which were certainly in evidence when I was chopping everything back. I will know what to look for next Spring and I will also think about spraying in early Spring but will have to consider this carefully since I am loath to use chemicals in the garden. One of the bits of advice was to encourage wildlife into the garden to eat the caterpillars. Well my garden is swarming with wildlife: birds, frogs, aphids and still I have this infestation so I don’t know what the answer is. If the plants are attacked as badly next year then I will think about removing the plants altogether which will be a huge pity as I love Solomon’s Seal.
So having spent half an hour going ‘yuk, yuk, yuk’ the caterpillars have been removed and there is a hole in the border. Hopefully I will have reduced the problem next year as apparently the larvae overwinter in the soil before laying their eggs next year and if I have removed the larvae, hopefully all of them, then this should break the cycle although of course there is nothing stopping more sawflies flying in.