**Swallow Bugs** (*Oeciacus vicarius*) are parasitic true bugs that specialize in feeding on the blood of cliff swallows, barn swallows, and other related birds. They are similar in appearance and habit to bed bugs, but they are adapted to bird hosts. The conflict is indirect human nuisance: when swallows migrate and abandon their nests (e.g., nests under eaves of homes), the massive numbers of hungry bugs migrate into the structure in search of a new host, causing **painful, annoying biting** of people and pets.
Taxonomy and Classification
Swallow Bugs belong to the order Hemiptera (True Bugs), family Cimicidae (which includes bed bugs). They undergo simple metamorphosis. They are highly efficient parasites, capable of surviving for over a year without a blood meal by hiding deep within the cracks and crevices of the abandoned mud nests and the structure itself.
Physical Description
Adult Bugs are small, 1/8 to 1/4 inch long.
- **Appearance (Key ID):** Flattened, oval-shaped body, reddish-brown to dark brown. They lack wings and have piercing/sucking mouthparts. They are hairier than bed bugs.
- **Habitat (Key ID):** Clustered in massive numbers within the material of the **mud swallow nest** and the immediately surrounding cracks of the structure (eaves, siding).
- **Conflict Sign (Key ID):**
- **Abandoned Nests:** Large numbers of active, tiny biting insects appearing suddenly inside a home shortly after swallows have migrated in the fall.
- **Bites:** Small, itchy, red welts, typically appearing in lines or clusters on exposed skin.
- **Conflict:** Severe biting nuisance following bird migration.
Distribution and Habitat
Swallow Bugs are found throughout North America and Eurasia, wherever their swallow hosts nest. Their habitat is the mud nest itself, the cracks around the nest, and the building structure immediately adjacent to the nest site.
Behavior and Conflict
The conflict is dominated by the seasonal migration into the home.
- **Evasive:** Like bed bugs, they are nocturnal feeders, hiding during the day in tight crevices.
- **Survival:** They can survive long periods without a host, meaning nests that are several years old can still harbor viable populations that will infest a home when the swallows leave.
- **Disease Vector:** While they can carry arboviruses, they are not typically considered a significant vector for human disease; the primary conflict is the severe biting nuisance.
Management and Prevention
Control requires eliminating the bird nest source and treating the structural harborages.
- **Remove Nests:** Once the swallows have left for the season (usually fall/winter), **remove all nests** (check local migratory bird laws first) and immediately dispose of them in a sealed bag.
- **Treat Site:** Thoroughly treat the area where the nest was attached (eaves, siding) with a residual insecticide dust or spray to kill bugs emerging from the wall.
- Seal all structural cracks and entry points between the nesting site and the interior of the home.
- If they are inside, treat cracks and crevices with a residual insecticide dust, similar to bed bug control.
Conservation and Research
Swallow Bugs are managed as high-priority nuisance pests associated with wildlife. Research focuses on their vector potential and developing non-chemical methods to deter swallows from nesting on residential structures.