How important is it to mention literary devices in essays?

Extremely important! It may seem like a very basic thing to do, but a lot of students spend too much time mentioning how the literary piece makes the reader feel and what it conveys, without mentioning specific literary devices. Sadly this does not get you a lot of marks in your essay!

Literary devices can vary from very simple, well-known ones like commas and caesuras, to more complicated ones like bathos and free indirect discourse. Mention as many as you can, (being sensible and making use of a good structure) and you will see how it gets easier to pick up those extra marks!