Unfortunately, nothing says "home of the mosquitos" more than Shadow Bay. Waldo Lake's southern end is notorious for being heavily infested with these nagging little critters.
It's a shame really, because Shadow Bay Campground is located on one of the most scenic lakes in Oregon, offers direct access to the water, and is well-built and well-maintained. It's not all for naught, however. Depending on the snowpack and early summer temperatures, mosquitos are typically at their worst from June through the end of July, yet the campground is open through the end of the summer. To avoid the crowds of North Waldo or Islet Campground, stake your tent here in late August and September, and you'll experience the campground's charm.
Interestingly, the campground offers a total of 92 tent/car campsites, by far the lake's largest quantity, with numerous 'multi-family' or double sites available. Reservations are only possible for 19 of these sites, however.
Note: Shadow Bay Campground is open from the end of June through the last Sunday in September.