Without a picture of the damage, but based on this time of year, I think it is earwigs. They chew irregular, variable-sized holes in leaves and can devastate seedlings. 

They are nocturnal so you can search for them with a flashlight. During the day they hide in moist, dark places, like under stones and debris.

They can be trapped using fish oils and cat food in small containers. There are also earwig traps you can buy, as well as baits. To make your garden less attractive to them remove debris and other places where they can hide.

You can find more information, pictures of the European earwig, and a listing of chemical controls in this link to the Pacific Northwest Insect Handbook: https://pnwhandbooks.org/insect/hort/landscape/common/landscape-earwig