They don’t, just the vast majority of them.
Termite scientists are a fairly conservative lot, and like patterns. Termes is a Latin word meaning wood worm. It is a widely followed convention that the genera of termites be given names with -termes at the end, but it isn’t required by the rules of naming animals. Just makes things easier I guess. Some genera don’t. This is because the taxonomist who authored them broke with convention. The best know of these is Zootermopsis, the dampwood termites of North America.