This is why it is so important to scrape termite shelter tubs when we find them during an inspection. When opened up, active worker termites will begin immediately repairing the tunnel/shelter tub to protect it from sunlight and dry environments. These tunnels are made from soil and wood combined with termite saliva as termites require moisture to survive and are vulnerable to dehydration. This is why it is important to maintain four to six inches of clearance between the soil and the top of your foundation wall. When your soil is in contact with the siding it becomes a vulnerable area for termite infestation.
Within two hours of breaking up this shelter tub, we found termite workers rebuilding it. It is very important to go back and check the broken tunnel for live termites. Also, they build the tunnels twice as fast when they have music playing in the background:)