The bears were there before the farms. If the farms are creating a lot of new moths that weren't otherwise there, Another possibility is the moths were there b

The bears were there before the farms. If the farms are creating a lot of new moths that weren't otherwise there, Another possibility is the moths were there before the farms as well, and the land they lived on now happens to have been turned into farmland. If that is the case than it's not as likely anymore that pesticides would bring an equilibrium. Maybe there were even more moths before it the land was one huge monoculture. (just spraying ideas here, I don't know what kind of land moths prefer nor if it really is a monoculture there)