Something very weird is going on this year in one of my beds. The other day while weeding, I noticed that the entire bed was covered (or should I say smothered) in small pale grey worms, who were systematically devouring my lysmacchia groundcover over the entire bed. The worms did not touch any other plants in the bed, and not even the OTHER groundcovers there (short veronica, thyme, ajuga, silver beacon). Any clues as to what it may be?

This week... no more lysmacchia and worms gone.