Termites in the garden threaten landscaping elements, wooden structures like fences and decks, and the adjacent home foundation. Since they feed on cellulose, any wood or plant material is a potential food source. Addressing a garden infestation requires unique strategies focusing on the soil and outdoor wood to eliminate colonies and prevent future invasion. Quick action is necessary to protect surrounding structures from damage.
Spotting the Signs of Termite Infestation in Garden Areas
Identifying termite activity early is crucial to minimizing damage and distinguishing it from wood rot. The most obvious indicator of subterranean termites is the presence of mud tubes—pencil-sized tunnels built from soil, wood debris, and saliva. These shelter tubes allow termites to travel between their underground colony and a food source while protecting them. Look for these structures along foundations, fence posts, retaining walls, or any wood that contacts the soil.
Another clear sign is the appearance of discarded wings or swarmer insects, the reproductive members of the colony. Swarmers emerge in large groups to establish new colonies, shedding their wings near light sources or wood entry points. Damaged wood often sounds hollow when tapped because termites consume the interior, leaving only a thin outer layer intact. Wood that appears soft, darkened, or has small exit holes may be actively infested, signaling a need for immediate intervention.
Non-Chemical Strategies for Termite Prevention
Prevention begins by modifying the garden environment to make it inhospitable. Termites are attracted to moisture, so managing drainage is paramount; ensure surface water flows away from structures and eliminate leaks. Keeping the soil dry near wooden elements removes a primary condition necessary for subterranean termite survival.
Eliminating all sources of cellulose-based food near vulnerable structures is a key preventative measure. This means removing old stumps, buried wood scraps, and piles of lumber. Replace traditional wood mulch with alternatives like rubber, stone, or pine straw near any wooden structure, as wood mulch provides both a food source and moisture retention.
Physical barriers can block termite access to vulnerable wood structures, such as raised beds or fence posts. One method involves creating a barrier of particle material (sand or crushed basalt) around the base. The particle size must be precisely calibrated—large enough that termites cannot move them, yet small enough they cannot tunnel through the gaps. For permanent protection, metal flashing can prevent direct wood-to-soil contact, forcing termites to build visible mud tubes over the barrier.
Eliminating Termites with Targeted Natural Controls
For gardeners seeking to eliminate termites without synthetic pesticides, several biological and non-toxic controls are available. Beneficial nematodes, such as Steinernema species, are microscopic roundworms applied to infested soil. These organisms seek out termites and release symbiotic bacteria, which rapidly kills the host insect.
Nematodes are typically mixed with water and applied as a soil drench in areas of known termite activity. Since they are living organisms, the soil must be kept moist for several days after application to ensure survival.
Diatomaceous earth (DE), a fine powder made from fossilized diatoms, is a physical control. DE works by scratching the termite’s protective exoskeleton, causing dehydration and death. This non-toxic powder can be dusted into dry voids or crevices where termites are active, but it loses effectiveness completely when wet.
For treating wood surfaces like fence posts or exposed lumber, a solution of boric acid, a naturally occurring mineral, is highly effective. Boric acid acts as a stomach poison, disrupting the termite’s metabolism and nervous system when ingested. It is often applied as a slow-acting dust or liquid borate treatment directly to wood, allowing termites to carry the toxicant back to the colony.
Choosing Effective Chemical Soil Treatments
When natural methods prove insufficient or the infestation threatens a home structure, applying a chemical soil treatment (termiticide) is necessary. Termiticides are liquid insecticides formulated to create a treated zone around a structure’s perimeter to block subterranean termites. These products fall into two categories: repellent and non-repellent formulas.
Repellent termiticides contain chemicals termites can detect and actively avoid, functioning as a physical barrier. This type requires a continuous application, as any small gap in the treated zone will be exploited.
Non-repellent termiticides are undetectable, allowing termites to tunnel through the treated soil. Termites that contact the chemical are killed slowly, allowing them to transfer the toxicant to other colony members through social interaction.
The proper technique for creating this soil barrier involves either trenching or rodding the perimeter. Trenching involves digging a shallow trench along the foundation, applying the liquid termiticide, and backfilling the treated soil. Rodding is an alternative technique where the termiticide is injected directly into the soil at regular intervals using a long metal rod. This method is used where a full trench cannot be dug, such as near sidewalks or dense landscaping. Always follow label instructions precisely and take precautions to prevent runoff.