After it rained in Guangzhou, many flying insects died automatically a few hours later. What is it? What should I do?

This species is called termites, also known as "water ants". They only eat wood, but they don't usually hide in it. If the nest at their roots is soaked by sudden heavy rain, they will run for their lives everywhere, so they are commonly known as water ants. If you accidentally breed a nest at home, you will often eat more than half of your wooden furniture before you find it.