A swallow bug is a small, parasitic insect that primarily feeds on the blood of birds. These creatures are closely associated with various species of swallows, nesting within their structures. While they mostly remain in their natural bird habitats, swallow bugs can sometimes become a noticeable nuisance when they inadvertently enter human dwellings.
Identifying Swallow Bugs
Swallow bugs typically measure between 3 to 5 millimeters in length, similar in size to an apple seed. Their coloration is usually reddish-brown, often appearing darker after they have fed, much like an engorged bed bug. When unfed, their bodies are flat and oval-shaped, allowing them to hide in narrow crevices.
They possess specialized mouthparts for piercing skin and sucking blood, their sole food source. A distinguishing characteristic that helps differentiate them from common household pests, like bed bugs, is their slightly longer legs and a more noticeably hairy body. Observing their location near bird nests further aids in accurate identification.
Their Natural Habitat
Swallow bugs are obligate ectoparasites, meaning they must live on the outside of another organism and rely on it for survival. Their primary hosts are various species of swallows, including barn swallows and cliff swallows. These insects spend the majority of their lives within the nests of their avian hosts.
They inhabit cracks and crevices within nest structures, remaining close to their food source. All life stages of the swallow bug require blood meals. Eggs are typically laid within the nest material, allowing their entire lifecycle to occur in proximity to the bird hosts.
Why They Enter Homes
Swallow bugs primarily enter human homes when their bird hosts abandon nests, usually after the nesting season concludes. Without their primary food source, the bugs disperse from empty nests in search of new hosts or shelter. This seasonal migration is the main reason they might appear indoors.
They commonly enter structures through various access points, such as cracks in foundations or walls, gaps around windows and doors, and uncovered vents. Attics or wall voids adjacent to active or recently vacated swallow nests also serve as direct entry routes. While their preference is bird blood, these bugs will bite humans or pets if no other food source is readily available.
Managing Swallow Bug Infestations
Managing swallow bug infestations begins with preventive measures, such as careful removal of swallow nests once the birds have departed for the season. Active nests are legally protected and should not be disturbed. Sealing potential entry points into the home, including cracks in foundations, gaps around utility lines, and ensuring window screens are intact, can significantly reduce their access.
For an active infestation, thorough vacuuming of affected areas, especially around windows, attics, and wall voids, can remove many bugs. Washing bedding and clothing in hot water and using a steam cleaner on carpets and furniture can also help eliminate hidden pests and their eggs. For severe or persistent infestations, professional pest control is often the most effective solution. Bites from swallow bugs are generally harmless, causing itchy red welts similar to mosquito bites, and can be managed with soap and water cleaning and the application of anti-itch creams.