They are likely to emit the smell when they are attempted to be moved from your home.
They can often be spotted around window frames.
Dr Glen Powell, Head of Plant Health at RHS Garden Wisley said the pheromone traps in their gardens enable them to “study invasive species from their arrival in the UK through to potential colonisation”.
He said: “While there is currently no evidence of breeding we would expect the stink bug to grow in prevalence and it may become problematic in gardens during summer and homes in the winter months within five to 10 years.
“This isn’t a sudden invasion but potentially a gradual population build-up and spread, exacerbated by our warming world.