What is the best homemade termite killer?

The best homemade termite killer that has some effectiveness for small, localized issues is a combination of boric acid or borax solution and orange oil, plus preventative measures like moisture control, though no homemade killer reliably eliminates large subterranean colonies with millions of members and professional treatment is recommended for structural infestations. A common homemade borate killer is mixing one cup borax with one gallon hot water and brushing or spraying it onto infested wood, as borates kill termites that ingest treated wood by disrupting digestion and providing long-term prevention, but penetration is limited to surface. Orange oil containing d-limonene extracted from orange peels can be injected directly into drywood termite galleries using a syringe to kill on contact, but it does not spread through entire colonies. Another homemade method is using white vinegar and lemon juice mixed, spraying directly on visible termites to kill some on contact due to acidity, but it does not reach underground nests. Diatomaceous earth, a natural powder made from fossilized algae, can dehydrate termites when dusted in dry cracks but must stay dry. Beneficial nematodes, microscopic parasitic worms purchased online, can be applied to soil to infect termites naturally. The most effective homemade approach is actually prevention, fixing leaky pipes, ensuring gutters drain away from foundation, ventilating crawl spaces, removing wood-to-soil contact, and keeping firewood away from house, because termites need moisture. For active infestations with mud tubes or hollow wood, the best killer is professional liquid termiticide barrier with fipronil costing $1,000 to $3,000 for full elimination within 30 to 90 days.