Worms are great for soil. They create large channels that encourage gas exchange and allow water and nutrients to penetrate deep into the soil. They also act as a little aerator benefiting the soil structure and they actually help to decompose thatch.
However they do cause problems when they surface, normally in the wetter winter months. They produce casts, which are little heaps of soil that have passed through the worm. These casts tend to smear on the lawn’s surface covering the grass beneath them and creating the ideal seeding ground for weeds and moss.
I can provide treatments which will not kill the worms but will encourage them to remain in the soil and carry on doing their good work.