You definitely do not have to treat all at once. A Termidor treatment can be spread out over a few weekends or whatever time frame you want to. Please read our "How To Do A Termite Treatment" article if you have not already. You are also welcome to call us with any specific treatment questions. We are here to help.
Yes, Termidor SC will kill wasps and it is labeled for wasps. However, Termidor SC is also labeled to only be used on a structure or immediately around the foundation of a structure. So, while it will not damage or harm the wood of the swing set it is not labeled to be used there. You can use a pyrethrin product such as Wasp Freeze to knockdown the wasps that are currently buzzing around. We do not recommend spraying anything directly onto swing sets as the children will come in repeat contact with the insecticides. Finding the wasp nest and treating it directly would be the most effective treatment. Some species of wasps can also be baited. You can set out an empty tuna fish can and see if the wasps are attracted to it. If the wasps are attracted to it, you can try baiting with our Yellow Jacket Bait Station Kit.