This is a worker European paper wasp, Polistes dominulus. They are accidental(?) arrivals from overseas, back in the 1990s. They quickly spread over the entire continent and have come to dominate the urban landscape. Watch out for their nests in cavities and sheltered situations (such as bird houses, including purple martin gourds). Individually, they are not bothersome, but they defend their paper combs vigorously! They are effective predators of caterpillars, which they chew up and feed to the larvae in the nest. This one is gathering wood to chew into pulp to expand the nest.