To apply Termidor SC to a home with a pier and beam foundation, you will need to trench around each pier. You will need to trench around any point where a support for the home touches the home. If the piers are hollow blocks you also have to drill a hole in each pier to treat the inside space where termites could potentially travel up without hitting the treated soil around the pier.
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.
As long as Termidor SC has time to dry and bind with the soil, the rain will not affect it. It is best to wait until you have a few days of no rain in the forecast so there is at least 24 - 36 hours time after you treat before it rains. After that it will hold quite well to rain and weather.
It is not necessary to make a re-application of Termidor SC if it was treated 48 hours prior to rainfall and had a chance to completely dry.