The Locust are everywhere will they damage my apple trees?

Do you mean periodic cicadas, i.e. 17 year locusts? if so, they will not do a great deal of damage to mature trees (but they will do some damage) but can kill trees under 5 years old with their egg laying.

Locust will devour anything green in it's path. There are several takes on controlling these insects. A gaggle of geese or ducks. Seriously. These guys can eat locusts till their bellies drag on the ground and they are fast and efficient.

Next thing drape netting over your apple trees to protect their foliage. Without foliage no apples, no tree.

Spraying insecticide would only help for a couple of days and constant spraying would be a solution to killing them. However, spraying could also be hazardous to your health and your fruit could be contaminated.

The very best solution is only what appeals to you. Also call your local county extension in your area to talk to a master gardener who will have good information on the locust problem in your area as well as ideal suggestions on how to protect your apple trees. Good Luck