Here in Spain the Olive Fly can be a problem also. It's really common to see plastic bottles hanging in the trees that have a solution in the bottom. The solution is more of an attractant then the olives themselves and the flies drown in it. In fact, I read somewhere that this method was developed here. Apparently it's very effective. It's talked about
here. Also completely organic as the chemicals don't touch the tree or the ground. There is also a plant called "False Yellowhead" (Dittrichia viscosa) that goes by the name of Olivada here. It's got an old special relationship with the trees, apparently, as it turns out it hosts the Lacewing and another Olive Fly predator (can't remember what) in it's dried flowers. We don't have any on our land but are looking hard for it. It's supposed to be a pretty tough pioneer and invasive in other parts of the world.
