Because they are a dangerous pest i would recommend calling the local orkin branch office and asking them to send over a highly trained orkin pest specialist.
Getting rid of wasps in attic.
Fill a shop vac with soapy water then place the head attachment near the source of the insects.
If your wasps have built a nest on the floor of your attic bomb style wasp poisons work very well.
You need to locate the nest first.
Leave the shop vac on for a few hours to catch as many of them as you can.
Locate the part of the attic where the hornets and wasps are coming and going.
Getting rid of the nest is a bit difficult as compared to a single wasp but if you take the appropriate measures you will surely be successful.
If the nest is a hanging nest make sure you purchase a spray with a projectile shot so that you can completely cover the nest with it.
It is very easy for wasps to get into attics normally due to openings around vents and or poor construction practices that leave big gaps between the sections of wood near the areas where the shingles and gutters meet up.
Spray the nest according to the directions on your spray.
The wasps and hornets will get sucked in to the vacuum and drown in the soapy water.