Several instances a disastrous and even fatal effects to valuable pearorchards from being attacked by the Psylla have come under my observation, as well as entirely satisfactory results from treating the trees.

The life-history and habits of injurious insects must be accurately determined before we can know just how to deal with them. A knowledge of the habits of such insects will also often enable the farmer to so manage his land crops that the insects are placed under unfavourable and even destructive conditions.