Toilet Drain And Gaps In Flooring Around The Waste Pipe

[Amyea]

Hi

In my bathroom there is a space in the floor behind the toilet where the drainage system goes but it's not tight to the floor, the hole where the drain goes is big so I get a lot of insects coming up through the hole. Can I block the hole with expanding foam or something? Will this damage the drainage pipe or is it just simply that whomever installed the toilet made too big a hole in the floor?

[proptech]

Hi
Any chance of a photo ? Not easy to answer you without knowing a bit more of the problem.