Black wasps

For 3 years in a row we have been finding black wasps in our house. Every summer 3 – 5 slowly come out of who knows where. Then we don’t see them again until the following year. Lucky my cats find them before my kids do.
The question is how do I find where they are coming from? Why do they keep coming back? Tecumseh

Wasps build new nests every year. The likelihood of new nests close to previous nests is high as the wasps go to where they think it’s a safe place to build. Seeing other nests in the vicinity makes that decision easier. 

I would suggest doing a walk through along the external perimeter of the house on a nice sunny day and observe where the wasps are entering the house. They need to access a void in order to build. Once located please contact a professional to treat. 

The wasps you’re seeing are probably ones that have lost their way heading out of the nest and then ending up on the inside. They will normally be slow moving as they have depleted their energy and gather by the windows, following the light in order to get out. 

Vacuum them off as spraying is a waste and detrimental to ones health on the inside.