While termites are often found in mulch, they need more nutrition than shredded wood can provide. According to the University of Florida Extension, mulch "increases the ability of termites to survive where they are already established by keeping the soil moist and temperatures moderate."
A 2-inch layer of mulch is enough for most garden beds. If the mulch is too deep, it provides a welcoming environment for the termites, and it can provide a "bridge" to a house, according to the University of Florida Extension. This allows the insects to reach the house and avoid contact with soil treated with termiticides. If your garden bed is next to a structure, such as your house or garage, do not let the mulch touch the building. Keep mulch and railroad ties at least 6 inches away from a foundation, and place your plants at least 3 feet away. Make sure the soil slopes away from the structure for good drainage, and keep gutters and downspouts working properly to direct runoff away from the building.
Check your garden beds for mud tubes, damaged wood and swarms of winged termites. Contact an exterminator if you see any of the signs. To protect your beds and your house, the University of Florida Extension recommends soil treatments, bait systems or wood protection measures obtained through a licensed pest control company. Never store mulch or railroad ties on the ground or directly next to a building.