Screeching insects

I’m going to take a picture of one of the little creatures that live on the trees at this time of year, if I can. They’re like cockroaches but they live in trees and they’re bark colour and don’t crawl/fly into your house. So I don’t mind them. But they’re VERY noisy. They make this kind of screeching sound - a bit like a thousand crickets gone crazy - possibly there are actually thousands of them in each tree, which is why they’re so loud.