Nematodes typically take between 3-7 days to kill termites. The nematodes seek out and enter the bodies of termites, where they reproduce, releasing a bacterium that will eventually kill the host insect. When nematodes first come into contact with termites they tend to penetrate their exoskeletons more slowly than other insects. After entering and reproducing inside the body of a termite, nematodes can quickly spread throughout a colony and overwhelm them within days.