Because of their
wood-eating habits, termites sometimes do great damage to buildings.
Their habit of building tunnels wherever they go and of remaining
concealed within the wood where they work often results in their
presence being unknown until the timbers, riddled with tunnels
until spongelike inside, give way. Once they have entered a building
they do not limit themselves just to wood, also damaging paper,
cloth, carpets, and other materials. In regions where termites
are plentiful, no timber in construction should be left in contact
with the ground. Exposed timber can be made resistant to attack
by impregnation with creosote or other chemicals, but the most
effective defence is a masonry foundation. Even so, termites are
able to build tunnels with walls of packed earth over several
feet of masonry or work through small cracks to reach wooden parts
of a building. When termites have already penetrated a building,
removing their means of access and destroying the colony with
fumigation are usually effective means of stopping further damage.
Another common method of treating termites in houses in Australia
is the use of arsenic trioxide powder. This is carried back to
the nest by the workers, killing the queen, and thus the nest.
Above Images Come From The USDA