The Audubon NAH1 Bird Feeder Hummingbird features small feeding ports designed specifically for hummingbirds, typically measuring around 0.125 to 0.25 inches in diameter, which are too small for most flies and insects to enter. These ports are tailored to accommodate the long, slender bills of hummingbirds while minimizing access to larger insects. However, it's essential to keep the feeder clean and regularly inspect it for any signs of insect buildup or blockage to ensure the best feeding experience for the hummingbirds.