Most covers and gutter screens attract wasps, hornets, yellow jackets, and bees. These insects are always looking for new homes, and covers and gutter screens provide a good location. Gutter Filler does not attract insects. Squirrels, chipmunks, and birds often use gutters for nesting (leaves and pine needles) and food sources. Squirrels have been known to chew through covers and gutter screens of a house, and birds often nest at the ends. Gutter Filler doesn’t provide a nesting area and prevents animal food from getting in. Therefore, animals will not be attracted there. When gutters clog, so do downspouts, creating a perfect environment for mosquitoes to breed. With Gutter Filler style products, mosquitoes are blocked from breeding.