Like it or not, wasps have an important place in the ecosystem. Predatory wasps eat other insects and may help control them. But wasps also can be aggressive. If you have wasps in cedar trees near your home or in another high-traffic area, they may need to be eliminated for safety reasons. The best way to do this is to call a professional. However, if you want to try to eliminate the wasps yourself, you should take certain precautions.
Protect yourself. This is probably the most important step in wasp elimination. Wear a long-sleeve shirt and jacket and a pair of thick, sturdy pants. Close off your clothing by wrapping duct tape around your cuffs and your neckline. This will keep the wasps out of the clothes if they attack. Wear a pair of goggles with sides. The more of your face they cover, the better.
Wait until nightfall. Unlike bees, wasps can be active during any time of day. However, there will be more wasps in the nest at night. Also, their visibility will be poorer at night, and their attacks less accurate.
Spray the nest with a wasp insecticide. Look for a brand that advertises instant kills and has a long spray arc. Creep up to the wasps' nest and apply the spray upward through the hole in the bottom of the nest. Keep spraying until you have a thick application.
Get out of the way. Some of the wasps may not be dead, just angry. Give them space until you see no more activity.
Check the nest in a few days. If you don't see any more activity, clear the old nest out of the cedar tree to discourage new tenants. If activity is still present, spray the nest again. Continue to spray at three-day intervals until all of the wasps are gone.