The first thing you need to remember is that it is perfectly fine to have a few insects in your house. In fact, there is no such thing as an insect-free house, so every house you go to, regardless of how clean it is, will have an odd spider, ant and the like here and there, and that is the norm. So, seeing a few scattered ant here and there is fine, however, if you have an infestation or a pest problem, you need to get it dealt with as soon as possible.
The most common types of pests that usually affect us are termites, ants, roaches, moths and rats to name a few. Having an infestation of any of these pests is a lot of problem, and you should try to call your residential exterminator and have them deal with it immediately. This is because each and every single one of these pests are nuisances and cause a lot of damage to us.
In case of a termite infestation, a really bad one can end up with the wood in your house going completely hollow from being eaten, compromising the structural integrity and overall stability of the wooden item. Plus, getting rid of termites is not easy, and then having to deal with damages worth thousands is another downside. Similarly, rats, roaches and so on are vectors for carrying numerous diseases, so it can end up putting the health of those around you, including yourself, at risk. Rats also tend to gnaw at wood and chew through wires, which can get very dangerous. So, once you have realized you might be having a pest problem, do not delay it because it will end up costing you a lot more in terms of both extermination, and damage and repair charges later on.