In summarizing briefly this paper the chief points presented are,- (1), that the emergence of adults from winter quarters, deposition of eggs and migration of larvae occur with very little intermingling at di8tinct time prriod8 and arc, to a large degree, coincident respectively with certain life events of the pear tree, as the swelling of the buds, development of the blossom clusters, and opening of blossoms; (2), that the psylla in each of its life stages is sensitive to certain spraying mixtures. Experiment in 1910 indicated the possiblitity of protecting pear orchards by a single treatment to kill either the adults, or eggs, or nymphs.