Hole in tree full of bugs,cleaned it out but how to fill it in?

I have a dogwood tree in my yard and just cut off a dying branch with a strange hole around it,kind of like a crack thingy?I was blowing away the sawdust when I saw something moving inside the crack,turns out it was about 20 earwigs.I used the jet setting on my hose to blast them out,but I have a feeling they will just go back inside it?Is there something around my house I can use to seal it off,but won't hurt the tree?Because if they do end up going back in,I don't want to be hosing them out every few weeks.I thought maybe candle wax?Please help!