I have an orchard of 60 fruit and nut trees and at one end I have five
hives of bees. Over the past several weeks we have been invaded by small
grasshoppers; they have apparently killed two first-year walnut trees and
badly damaged a cherry tree.  I could not repeatedly pick off or knock off
enough grasshoppers to save these trees, so I sprayed the nearby trees most
affected by the pests with insecticidal soap (potassium salts of fatty
acids) on a late afternoon with almost no wind, after my bees had mostly
stopped foraging. (I am trying to use "organic" methods) Two days later the
hoppers were back, so I tried parafinic oil.  This part of the orchard is
about 150 ft (50 meters) from the hives and long past bloom.  I have seen
no increase in bee mortality.  But, I am wondering, what if the problem had
occurred next to the hives?  I can think of a lot of methods to try, but I
would like to hear from people who  have had some practical experience with
methods that work.