In the not too distant future, tiny robots will detect pests on produce and emit a signal to shoo them away.
For piercing-mouthed pests like Aphides no wash is of use unless it contains a basis of soft soap. This softsoap wash kills by contact, and may be prepared in the following way: - Dissolve 6 to 8 lb of the best soft soap in boiling soft water and while still hot (but of course taken off the fire) add 1 gallon of questions involved, under their own headings.
One of the worst pests of pear trees is the pear midge, known as Diplosis pyrivora or Cecidomyia nigra, the females of which lay their eggs in the flowerbuds before they open.
Cereal pests can only be treated by general cleanliness and good farming, and of course they are largely kept down by the rotation of crops.