It's not exactly a joy to enjoy Rhenish Sauerbraten and "Hämchen" (Haxe) at Cologne's Altermarkt this August. The air shimmers with heat. At the outside tables of the brewery, guests are constantly waving their arms wildly and twirling beer coasters back and forth. They don't fan cool down. they fight back. Because they are constantly visited by wasps. The insects seem to like the succulent specialties even more than the guests themselves.