Many people have asked me if red wigglers can compost wood chips. Thankfully, they can, and the resulting castings are of excellent quality. With that said, using this material warrants caution and special preparation is required in order to compost wood chips.
Firstly, make sure that you do not use cedar, walnut, juniper or other similar types of trees.
These trees contain resinous compounds that can be residual and will harm both your worms and garden plants.
Secondly, make sure that the wood chips you use have been aged and leached by the rain for quite some time.
Fresh wood chips do not hold on to moisture very well and will in turn create a dry environment in your bin that can hurt your worms. Aged wood chips on the other hand hold onto moisture, and create a good habitat for your worms to live in. Also, aged wood chips are generally populated by beneficial fungi, which aid the worms in the decomposition of the substrate.
Lastly, when you use wood chips, make sure that they aren't the only material in the bin.
Red wigglers do not thrive in a system entirely composed of wood chips. They need nitrogen materials in the mix as well, to ensure a correct carbon to nitrogen ration for microbe population growth and decomposition. I recommend mixing aged rabbit, cow or horse manure with the wood chips in order to create a good habitat for your red wigglers. Veggie and fruit scraps also add nitrogen to the mix and help balance an ecosystem that is carbon heavy due to the presence of the wood chips.
If you are looking for a wood-based material that is useable immediately, then I recommend kiln dried pine shavings. I have found this material to be an excellent carbon source. I actually prefer it to peat moss when starting a worm bed. It lasts longer than peat in the substrate, has good air flow, and breaks down into wonderful worm castings over time. You will need to mix in with aged manure compost in order to get good results with it, and the shavings must also be soaked all the way through with water before you mix them up. Without soaking, you may have dry pockets in your worm bin initially, which can cause your worms to leave a new worm bin.