Adult wasps consume liquid forms of sugar as their primary diet, so are drawn to flowers, sap flows, fallen/rotting fruits, hummingbird feeders, and (if available, like at a picnic) human foods/drinks. Therefore, it would be difficult to discourage them from visiting the tree unless the sap flow stops on its own. (Why sap is oozing is hard to determine...it could be a harmless phenomenon, or an indication of a problem like borers or decay in the wood. If you have concerns about tree health, have a certified arborist or licensed tree expert evaluate the tree.)

To more permanently resolve the problem, the nest itself would need to be eliminated, which usually involves the use of a pesticide (wasp spray). Our Social Wasps web page provides information about what to look for in searching for nest sites. If it can't be found, then there is little recourse except to avoid the area while the adults are actively visiting a sugar source. We don't have research about using a pesticide as a repellent, so treating the sap site with insecticide would probably not accomplish much, or could risk harming beneficial insects also visiting the sap as a sugar source (native bees, certain butterflies, etc.) because the type of chemical involved would not affect only wasps. There isn't a way to stop the sap from flowing directly, though it may stop on its own, nor would you want to cover it up with a physical barrier or sealant, as that could worsen the tree's condition in case wood decay was present. (Pruning cuts should not be coated in tar for similar reasons, despite horticulturists formerly recommending the practice. We now know that such actions risk more damage to the tree, and letting pruning cuts seal-over at their own pace is best.)


Miri