Termites are known as destructive pests of wooden structures, but they also threaten potted plants, garden beds, and landscaping. Since these insects feed on cellulose, the main component of plant cell walls, any plant material, living or dead, can become a food source. Addressing an infestation requires accurate identification, targeted removal, and long-term prevention.
Identifying Termite Infestation in Plants
The first indication of a problem is often a decline in plant health, such as wilting or stunted growth, even when watering practices are correct. Termites consume the roots and tunnel up the stems, compromising the plant’s ability to absorb water and nutrients. Inspect the soil and the plant’s base for visual evidence of their activity.
Subterranean termites, the most common type to infest plant soil, build distinct mud tubes to travel safely between their underground colony and a food source. These pencil-sized tunnels, constructed from soil and saliva, may be visible extending up the side of a pot or along the base of a plant stem. Drywood termites, in contrast, often leave behind frass, tiny, granular fecal pellets that resemble fine sawdust or sand near an exit hole in the plant material.
Winged insects emerging from the soil or plant are reproductive termites, known as swarmers, which signals an established colony is nearby. Distinguish these from flying ants, which are harmless to plants. Termite swarmers have straight antennae, a broad waist, and four wings of equal size and length, while flying ants have distinctly bent antennae, a pinched waist, and two front wings that are noticeably larger than their hind wings.
Non-Chemical Removal Methods
Initial treatment should focus on hands-on, non-toxic solutions, which are often sufficient for localized infestations in potted plants or small garden areas. The most immediate step is physical removal, which involves carefully taking the plant out of its pot or soil bed. Gently wash the soil from the root ball with a steady stream of water to dislodge active termites and destroy their tunnels.
For potted plants, environmental controls can be highly effective against termites, which are sensitive to light and dehydration. Temporarily placing the infested pot in direct sunlight can drive the termites out of the soil and stems. Alternatively, submerging the entire pot in a bucket of water for 20 to 30 minutes may drown the subterranean termites, though this method should be used cautiously to avoid over-stressing the plant.
Natural deterrents provide ongoing protection within the soil environment. Diatomaceous earth (DE), a fine powder composed of fossilized algae, works through physical action, abrading the termite’s exoskeleton and causing fatal dehydration. Food-grade DE should be lightly dusted onto the soil surface, but it must be kept dry to maintain its effectiveness. Another biological control option is introducing beneficial nematodes, such as Steinernema carpocapsae, which are microscopic worms that parasitically target the termites in the soil without harming the plant.
Targeted Chemical Treatments
When non-chemical methods fail to control a persistent infestation, targeted chemical applications become necessary. Always choose a liquid termiticide or insecticide explicitly labeled for use on ornamental plants or the specific edible plant you are treating. The most common active ingredients suitable for this application are pyrethroids, such as bifenthrin, and neonicotinoids, like imidacloprid.
Imidacloprid is a systemic insecticide that, when applied as a soil drench, is absorbed by the roots and translocated throughout the plant’s tissues, killing termites that feed on the roots. Bifenthrin works as a contact poison and soil barrier, killing termites that move through the treated area. The application method is crucial and involves mixing the concentrate according to the label’s instructions.
The treatment is applied as a soil drench around the base of the plant, ensuring the solution is poured onto the soil and not the foliage or trunk. Prior to application, remove any mulch and pre-moisten the soil to help the product disperse evenly into the root zone where the termites are active. Always wear appropriate personal protective equipment (gloves and eye protection), and keep children and pets away until the solution has dried.
Preventing Future Infestations
Long-term protection involves making the environment less appealing to termites by managing moisture and removing potential food sources. For potted plants, using a sterile, cellulose-free potting mix reduces the initial risk of bringing termites home. Elevate pots off the ground using pot feet or bricks to prevent subterranean termites from easily accessing the drain holes and soil from the surrounding landscape.
Moisture control is a primary defense, as termites are heavily attracted to damp soil, which is essential for their survival. Proper drainage is necessary, especially in garden beds, to prevent standing water or overly saturated soil near the base of plants. Adjusting irrigation systems or using drip lines instead of sprinklers helps avoid excessive watering that creates the moist conditions termites prefer.
The final preventative measure is meticulous cleanup of cellulose debris, which serves as a food supply for foraging termites. Regularly remove fallen leaves, dead wood, old stumps, and other organic matter from near garden beds and potted areas. Avoid wood-based mulch directly against the base of vulnerable plants; alternatives such as stone, gravel, or rubber mulch do not provide the cellulose that termites seek.