Moisture content is very important when composting with worms. This is because your red wigglers breathe through their skin and need appropriate moisture to do so. Often times the materials you add will give your bin moisture, but you will find that you will need to add water to obtain appropriate moisture content (especially with warmer weather).
Check your bin: To check your moisture content reach into your bin and grab a handful of the contents. It should feel like a wrung out sponge with few drops of water.
Too dry: A good thing to have near your worm is a spray gun, especially when the weather is a bit warmer. Lightly spray the contents of the bin until it reaches the “wrung out sponge” moisture content.
Too wet: Add some dry shredded paper. This will soak up the excess moisture and your worms will eat it too! Be sure to double check your worm tea level as well as this can often affect the moisture content of your bin. If your collection try is overflowing with worm tea it may be adding extra moisture to the bottom level causing it to be too wet.