Wasps can be distinguished from bees by their smooth, rather than hairy, bodies. Very protective of their nests, the will defend against invaders with painful stings. The common bee sting, while harmless to most people, can be very painful.
Bees and wasps like to invade the warm sides of the structure and enter through, vents, and holes around wires. They also like to build nests on and under decking as well as under sofets and in peaks and eves.
An exterior treatment of the structure will keep them from entering and building on your structure for the season.