Certified GKH Gardening Expert
Half the battle with insect pests is enhancing natural resistance through good soil fertility and water management. Fertilize with a complete organic fertilizer, mulch and water appropriately and you will not have such stressed and susceptible trees.
If the pear trees and others are still dormant (no flowers or foliage), then use a dormant spray with a 2% solution of horticultural oil (2.5 ounce in 1 gallon of water). If in flower, then wait until flower drop to avoid spraying pollinators, then use the same oil but in a "delayed dormancy" 1% concentration (1.25 ounce per gallon).
Or begin spraying every two weeks with 70% neem oil.
For the pears and fireblight prevention, you can add a biological fungicide-bactericide to the tank mix now and weekly until flower buds open.
Inspect the pears weekly for fireblight infected tips (dried foliage with blackened "shepherd's crook" tips of woody stems. Prune those out below the blackened lesions before the infections advance downward into larger branches.