Norway Rat (Rattus norvegicus) High Risk

Norway rats are the dominant rat species in the Green River Valley industrial and commercial corridor. They are heavy-bodied rats with blunt snouts, small ears, and a tail shorter than their body. Adults weigh 7–18 ounces and measure 7–9 inches body length. Their fur is coarse brown or grey on the back, paler on the underside.

Signs of Norway rats in your Kent home:

• Droppings: ¾ inch long, capsule-shaped, blunt ends — typically found along wall-floor junctions and near food sources
• Burrow holes in soil near the foundation, under concrete slabs, and around dumpsters
• Gnaw marks on structural wood, electrical wiring, and plastic pipes — large, rough gnaw marks
• Grease marks (dark smears) along established runway routes
• Scratching and movement noises from crawl space or under floors, primarily at night

Norway rats are excellent swimmers and use storm drains extensively. King County’s drainage infrastructure — particularly in the Kent valley industrial corridor — supports large Norway rat populations that periodically expand into adjacent residential neighbourhoods.

Roof Rat (Rattus rattus) High Risk

Roof rats are slender, agile rats with large ears, pointed snouts, and tails longer than their body length. Adults are 6–8 inches in body length. They are black to dark brown and are excellent climbers — they move from tree canopy to roof eaves to attic spaces following established routes through mature residential neighbourhoods.

Signs of roof rats in your Kent home:

• Droppings: ½ inch long, spindle-shaped, pointed ends — found in attic insulation, along rafters, and near roof entry points
• Compressed runs through attic insulation (visible as dark tunnels)
• Gnaw damage at roof-wall junctions, fascia boards, and around utility entries
• Scratching and rolling sounds from the attic or ceiling at night
• Fruit and nut damage in yard trees adjacent to the structure

Roof rats are prevalent in South King County neighborhoods with mature tree canopy — particularly East Hill, Kent’s older residential grid, and Covington. Any branch touching or overhanging the roofline is a direct entry highway.

House Mouse (Mus musculus) Medium Risk

House mice are small (3–4 inch body), grey-brown with large rounded ears and a thin, semi-hairless tail. Their small size — a mouse can compress through a gap as small as ¼ inch — means they access structures through routes that would stop a rat.

Signs of house mice in your Kent home:

• Droppings: ⅛ inch, rod-shaped with pointed ends — found scattered throughout kitchen and pantry areas, behind appliances, and inside cabinets
• Gnaw holes in cardboard packaging and food containers
• Nesting material shredded from paper, insulation, and fabric in wall voids and drawers
• Musky odour in enclosed areas where mice are active
• Movement sounds in walls and under floors, often at night

Odorous House Ant (Tapinoma sessile) Low Risk

Odorous house ants are the most common ant species encountered in King County residential properties. They are small (1/16–⅛ inch), dark brown to black, and produce a distinctly rotten coconut or blue-cheese odour when crushed — this smell is the definitive identification marker.

They travel in defined single-file trails along baseboards, plumbing runs, and exterior foundation edges. Colonies are large (up to 100,000 workers) and highly mobile — queen relocation in response to disturbance means improperly applied repellent sprays often split colonies and spread the infestation.

Treatment note: Odorous house ants require slow-acting gel bait placed along active trails — not repellent sprays. Repellent sprays cause colony splitting and make infestations worse.

Carpenter Ant (Camponotus spp.) Medium Risk

Carpenter ants are the largest ants found in Pacific Northwest homes — workers measure ¼–⅝ inch. They are typically jet black, though some species have reddish-brown bodies. They excavate galleries in wood to nest — they do not eat wood, but eject it as distinctive sawdust-like frass.

Signs of carpenter ants in your Kent home:

• Sawdust-like frass (fine wood shavings mixed with insect parts) in windowsills, basement floors, and near wood structural members
• Audible rustling from inside walls or wooden beams, particularly at night
• Large black ants appearing indoors — especially in spring when colonies produce winged reproductives
• Moisture-damaged wood (carpenter ants prefer to excavate soft, moist wood — look for wood with fungal discolouration)

Carpenter ants in South King County are strongly associated with moisture-damaged wood in crawl spaces and near roof leaks. Resolving the moisture source is essential — treating ants without addressing moisture damage produces only temporary results.

German Cockroach (Blattella germanica) High Risk

German cockroaches are the most medically significant pest in residential and commercial environments. They are small (½–⅝ inch), light tan to brown, with two parallel dark stripes running lengthwise behind the head. Their wing pads are visible but they rarely fly.

German cockroaches are prolific breeders — one female produces 4–6 egg cases in her lifetime, each containing 30–40 eggs that hatch in 28 days. A single pair can theoretically produce thousands of offspring within months. They are strongly associated with kitchen environments and are found in wall voids near heat sources, behind refrigerators, inside dishwashers, and within electrical outlet boxes.

Signs of German cockroaches:

• Black pepper-like droppings in corners of cabinets, along hinge edges, and inside appliances
• Brown egg cases (oothecae) in harborage sites — 8mm long, rectangular
• Musty, oily odour in heavily infested kitchens
• Live nymphs visible at night when kitchen lights are turned on
• Smear marks where cockroaches travel across damp surfaces

King County Public Health identifies cockroach allergens as a significant trigger for asthma in children — particularly in multi-unit housing. See the full guide on signs of a cockroach infestation in Kent, WA for a detailed identification and response protocol.

Western Yellowjacket (Vespula pensylvanica) High Risk

Western yellowjackets are aggressive social wasps that nest in the ground, wall voids, and structural voids. They are ½–¾ inch, bright yellow and black, with no hair (distinguishing them from bees). Colonies can contain 1,000–4,500 workers by late summer. They scavenge aggressively for protein and sugar and will sting repeatedly without dying.

Signs of yellowjackets in your Kent property:

• Ground nest: high traffic of wasps entering and exiting a hole in the lawn, under a concrete step, or at the base of a shrub
• Wall void nest: wasps entering and exiting from a crack in siding, a gap in eave trim, or a hole in stucco
• Visible paper nest (rare for yellowjackets — more common for aerial nesters)
• Increased wasp activity around outdoor dining, rubbish bins, or compost

Yellowjacket nests in wall voids are the most dangerous scenario — disturbing the void (drilling, impact, vibration) causes the colony to penetrate through walls into the interior. Never attempt DIY treatment of a yellowjacket nest in a wall void.

Bald-Faced Hornet (Dolichovespula maculata) High Risk

Bald-faced hornets are large (¾ inch), black with distinctive white facial markings. They build football-shaped grey paper nests in trees, shrubs, and under eaves. Unlike yellowjackets, their nests are exposed and visible. Colonies contain 100–700 workers by late summer. They are highly defensive within 3 feet of the nest entrance — approach triggers aggressive stinging from multiple workers simultaneously.

Nests found in low-traffic locations (high in a tree, under a rarely-used deck) can often be monitored through the season as colonies die off naturally in winter. Nests within 10 feet of a high-traffic area require professional removal.

Western Subterranean Termite (Reticulitermes hesperus) Very High Risk

Western subterranean termites are the primary structural pest species in King County. They live in underground colonies and build mud tubes to travel from soil to wood — protecting them from desiccation during above-ground movement. Worker termites are creamy white, blind, and ⅛ inch long. Swarmers (reproductive alates) are dark-bodied with equal-length wings and emerge in late winter to early spring on warm, humid days.

Signs of termite activity in Kent homes:

• Mud tubes on foundation walls, piers, and floor joists in the crawl space — range from pencil-width to several inches wide
• Hollow-sounding wood when tapped — termites consume wood from the inside out, leaving a thin shell
• Bubbled or blistered paint over wood surfaces (termites introduce moisture into wood)
• Wings shed by swarmers near windowsills and sliding doors in late winter or early spring
• Visible damage to structural wood in the crawl space — damaged wood has a layered, honeycombed appearance

Western subterranean termites are active year-round in Kent’s mild climate. Unlike in dry climates where termites are seasonal, Pacific Northwest subterranean termites feed continuously through winter when soil temperatures remain above 50°F — which they do throughout most of King County’s winter months.

Bed Bug (Cimex lectularius) High Risk

Bed bugs are small (⅛–¼ inch), flat, oval-shaped insects that are apple-seed shaped before a blood meal and balloon-like afterward. Unfed adults are brown; fed adults are reddish-brown. They are strictly nocturnal feeders that shelter in harborage sites within 5–8 feet of a sleeping host.

Signs of bed bugs in Kent homes:

• Rust-brown staining on mattress seams, upholstered headboards, and box springs — faecal spots from digested blood
• White oval eggs (1mm) and translucent shed skins in harborage sites
• Sweet, musty odour in heavily infested rooms
• Bite marks in linear or clustered patterns on exposed skin (arms, neck, shoulders)
• Live bed bugs in mattress seams, behind headboards, in electrical outlets, and within picture frame backing

Bed bugs in South King County are most commonly introduced through travel to hotels, purchase of secondhand mattresses or furniture, and movement between units in multi-unit housing. They do not indicate poor hygiene — they respond to human presence, not cleanliness.