Make a safe spray to kill yellowjackets in small areas. Pour 2 parts liquid dish detergent and 1 part water into a large squirt bottle and screw on the top. Shake the bottle to combine the mixture.
Spray the yellowjackets you can see with the soap mixture. The yellowjackets will fall to the ground and die. Rake up and dispose of dead insects to avoid attracting others, such as ants and beetles.
Create traps to get rid of yellowjackets in larger areas. Purchase and thaw pieces of beef liver. Cut a grid of crisscrossing lines on both sides of each piece of liver with a sharp knife.
Fill plastic buckets with 1 part water and 2 parts liquid dish detergent. Make one bucket and one piece of liver for each area where you have observed yellowjackets. Position the buckets under nearby structures like fences, arbors and trees.
Hang the liver from the structures over the buckets with clear fishing line. The yellowjackets will be attracted to the liver and will gorge themselves on it. They will become too heavy to fly, then fall into the buckets and die.