Hiya!
Its been a while since I wrote anything on termites. After a 2 year long termite experiment with various genuses and different localities, I found that termites prefer to nest in certain cellulose-based substrates more than others. Here they are!
(ranked from 1 being the best and 5 the worst, even though these are preferable termite substrates)
[assume that all substrates must be dampened for termites, since they can only eat dampened sources of cellulose]
{for king & queen pairs and small worker groups, ant-setup test tubes are better, with a dampened piece of paper or cardboard fit to the lower half of the tube. Smaller diameter is better. The substrates listed are better for large colonies, satellite nests, or displays}
Subterranean (shy, common, and less likely to build mud tubes, like Reticulitermes)-
1. Coconut fiber mixed with aged aspen bedding
2. Native soils mixed with small pieces of oak bark
3. Coconut fiber (nothing else)
4. Coconut fiber mixed with native soils
5. Shredded rotting wood
Fast-spreading Subterranean (aggressive and more likely to build mud tubes, like Coptotermes. Nasutitermes probably would be able to survive with these)-
1. Large (1 inch or so) chunks of rotting wood mixed with coconut fiber
2. Native soils mixed with large chunks of rotting wood
3. Coconut fiber, native soils, and aspen bedding (fresh)
4. Dampened cork bark with coconut fiber
5. Coconut fiber & cardboard (fresh, but beneficial bacteria, such as the species sold in Tetra's SafeStart, could be added to help decompose the wood at the termites' natural feeding rate)
Dampwood (large and reclusive, like Zootermopsis. Mastotermes might be able to survive with these)-
1. Shredded rotting wood
2. Coconut fiber mixed with aged aspen bedding
3. Aged aspen bedding
4. Coconut fiber
5. Shredded cardboard & tissue
Drywood (small, reclusive, and bizarre, like Cryptotermes)-
1. Coconut fiber
2. Shredded cardboard
3. Cotton-based tissue
4. Rotting wood (but less damp than what is given to dampwood and subterranean)
5. Aged aspen bedding
Feel free to add some other good substrates that you've had experience with! There are many varieties of termites missing from this list, so adding a few would be great.