Is biological pest management a public good?

摘要

I would like to thank the group of men and women who recently came to rid my wheat ofblackgrass.1 tried to thank them on the day, but my Romanian was as good as their English and, frankly, I can't blame them for wanting to clear off as quickly as possible - it's not a job I would fancy every day for weeks on end. I do hope they can continue to come back every year.