Why are there always many flying insects at Loudaokou?

It turns out that our family also has it. It's called moth sodium, which is related to the feces and leftovers in the rotten trash can, and it is easy to cause gastrointestinal infection. Taiwan Province Province has a lot of information about its research, so I won't give you a long piece of information copied from the Internet. Let me tell you something about me. Our household is a toilet, and the seam between the toilet and the floor is not tight because of its age. At night, the little black fly will fly out of the joint. Later, my family got a new toilet. When I turned the old toilet upside down, I found eggs everywhere where the toilet touched the floor, so I cleaned it with high concentration of excellent chlorine (available in pharmacies). Later, the joint between the new toilet and the floor was tightly sealed, and the new toilet was straight-flush. Later, it was found that there was a sewer in the kitchen that was never used to connect the drain pipe of the washing machine. As soon as the disinfectant was poured in, it flew out a lot. Then it was sealed with cement, and then it was gone. Also, you can see if the water pipes in several bathrooms in the kitchen are not well sealed. Originally, I checked a lot of information, and everything about ventilation was solved, but it was still a lot. It was not until I changed the toilet and sealed the sewer that the problem was fundamentally solved.