If you notice tubes like this running from your dirt to up under your siding via the foundation, beware! These are subterranean termite tubes! These termites will get into your walls and wreak havoc! Possibly not even noticing trouble until a LOT of damage is done! This is a good reason to keep your foundations clean and free from dirt buildup. If you have foundation plantings, make sure you can see past the plants to keep your eyes on the health of your structure!