It seems really early in the year to be thinking about Box Elder Bugs but this is the time of year to work at preventing an infestation next fall. Use a tube of calking to seal up sites where the bugs can enter the house. Check cracks in the foundation or house siding and gaps around the windows or doors. It may seem like a big job, but with the arrival of nice weather you can break the job down into smaller parts. Perhaps do one side of the house every week this month.
Later in the year, you can spray massing box elder bugs with Sevin, Diazinon, or Orthene. You can also make a spray of soapy water using 5 tablespoons of liquid detergent per gallon of water. This is a very effective spray but does not have any residual effect.
Take a little time this summer to slow or eliminate the entry of Box Elder Bugs into your home.