What is a fly to a giraffe? It’s difficult to imagine a single insect even coming to the attention of these peculiar animals, which weigh in at thousands of pounds and routinely stretch their necks to heights of more than 14 feet. In Uganda’s Murchison Falls National Park, however, Michael B. Brown, a wildlife conservation researcher, has noticed something that might be harder to ignore: Whole clouds of insects swarming around the necks of these quadrupedal giants. Under ordinary circumstances,