Mosquitoes, of course.
In addition, I would look for moose down toward the river, especially in some of the ponds earlier in the morning. Caribou are where you find them, but I don't know the specifics of Wonder Lake. In September they migrate through there in good numbers. Loons are much easier to photograph on ponds, rather than the larger lakes. If you are talking early July, keep your eyes peeled along pond margins for nesting loons. There's every possibility of tundra swan pairs on some of the ponds, too. I have seen sandhill cranes in fair numbers later in the fall, but no info about July. Willow ptarmigan will be plentiful, especially up in the more open areas along the road toward Kantishna. I have seen plenty of bears feeding on blueberries later in the fall, but in July I would expect them to be grazing on grasses and digging for ground squirrels. I am not acquainted with any of the bears in the immediate vicinity of Wonder Lake, but I encounter a couple of distinct individuals back up the road toward Eilsen a few miles on every one of my visits. Wolverines are unlikely, but foxes are pretty widely distributed. From experience I am sure that you are aware you need to walk around the lake towards Kantishna for reflections of McKinley. There's also a great pond on that route for good reflections, but I don't remember its name.