The answer to 'why is my wasp droppings' is that you likely have a wasp nest near your home. Wasps build nests and deposit their droppings, which can appear as unsightly stains or spots around the exterior of your home. Wasp droppings are usually a white or yellowish color and can be found on walls, windows, and other surfaces near the nest.
Wasp nests are typically constructed in hidden or protected areas like under eaves, in attics, or inside wall voids. As the colony grows, the nest and droppings will become more visible. Wasps are attracted to sweet foods and drinks, so spills or crumbs around your home can also draw them in.