Hummingbirds also take sugar-water from bird feeders. The fantails are small insectivorous birds which are specialist aerial feeders. House finches are aggressive enough to drive other birds away from places such as feeders. White granulated sugar is the best sweetener to use in hummingbird feeders. Brown Bullheads are omnivorous benthic bottom feeders. Contaminated fomites such as clothing, food, cages, bedding, feeders, and water also spread the virus. Opportunistic feeders (particularly birds) move in to take advantage. It is a regular visitor around bird feeders. Young stick insects are diurnal (daytime) feeders and move around freely, expanding their foraging range. Most molluscs are herbivorous, grazing on algae or filter feeders. Carrion feeders attracted to the carcasses are then also killed. Osteoglossids are carnivorous, often being specialized surface feeders. Sphingid larvae tend to be specific feeders, rather than generalists. Demersal fish are also known as bottom feeders and groundfish. All species are generalist and opportunistic feeders.