Multifamily Pest Reference · Free tool

Wasatch Front Multifamily Pest Field Guide

The pests most often found in Wasatch Front apartments: how to tell them apart, whether they matter, what to do, and whose job it is.

Prepared by Trenton S. Frazer, M.S., Board Certified Entomologist (BCE #B3413) · Version 1.0, October 13, 2026 · Not legal advice

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Leave it No health or property concern in normal numbers. No treatment needed; reduce what attracts it.

Watch it Note where and how many. Fix the condition that brings it in. Treat only if numbers build or it moves indoors.

Act on it Report and respond now. Identify, inspect neighboring areas, treat or exclude, and follow up to closure.

Whose problem is it?

Responsibility depends on where the property is and how it is funded. The rules below are quoted and sourced on Utah and the Wasatch Front and HUD Multifamily Bed Bug Rules.

Salt Lake City: once infestation is proven, the owner starts pest control (SLC Code 18.96.050(S)). Salt Lake County: the owner or manager is responsible for vermin control, and contracts do not remove that duty (Health Reg. #3, 4.1.6 and 3.6).
Weber and Morgan counties: the owner handles infestations in two or more units or in shared areas; the occupant handles a single infested unit, unless the infestation comes from the owner's failure to keep the dwelling vermin-proof; a professional is required if the owner's methods fail (Housing Reg. 4.1.8).
HUD Model Lease properties: the lease requires the landlord to provide extermination as necessary, and HUD's 2019 clarification limits charging residents to cases of shown carelessness or neglect.
Everywhere: residents report pests promptly and prepare for treatment; a resident who cannot do the preparation should ask for help. Lease terms can allocate some duties where the law allows; check the lease and the rules above.

The pests

German cockroach Blattella germanica Act on it

How to recognize it: About 1/2 inch, light brown with two dark stripes behind the head. Found indoors in kitchens and bathrooms; small nymphs in cracks near warmth and water. Seen in daylight usually means a crowded population.
Does it matter?: Yes. Lives and breeds entirely indoors, spreads between units through shared walls and plumbing, and its allergens are associated with asthma. A NSPIRE deficiency in assisted housing.
What to do: Inspect the unit and the units around it. Professional baiting in harborage, removal of food and moisture, sealing of gaps. Store-bought sprays can drive them deeper into walls and keep them off baits. Follow up until no live cockroaches are found.
Who handles it: Pro. Resident clears cabinets, stores food sealed and takes out trash nightly.
Protected?: No.

Oriental cockroach Blatta orientalis Watch it

How to recognize it: About 1 inch, shiny dark brown to black; females nearly wingless. Slow-moving, found at ground level, in basements, crawl spaces, floor drains and around foundations.
Does it matter?: Sometimes. Usually comes in from outside or from drains and damp areas rather than breeding in living space; numbers indoors point to moisture or an entry route. Counts as evidence of cockroaches under NSPIRE.
What to do: Find and fix the moisture and the entry (door sweeps, drain traps, foundation gaps). Exterior and crawl-space treatment where numbers justify it.
Who handles it: Owner and maintenance (exclusion, moisture); pro for treatment.
Protected?: No.

American cockroach Periplaneta americana Act on it

How to recognize it: About 1-1/2 inches, reddish brown with a pale band behind the head; flies. Associated with sewers, steam tunnels and boiler rooms.
Does it matter?: Yes when it appears in units: usually means a path from a sewer or utility space, such as a dry floor-drain trap or an open pipe chase.
What to do: Find the source: dry traps, broken cleanouts, open chases. Seal and refill traps; treat the source area.
Who handles it: Owner and maintenance; pro for treatment.
Protected?: No.

Bed bug Cimex lectularius Act on it

How to recognize it: Adults about 3/16 inch (apple-seed size), flat, reddish brown, wingless. Eggs are white and about 1 mm. Signs: dark fecal spots on mattress seams and furniture joints, cast skins, live bugs. Bites alone do not identify bed bugs.
Does it matter?: Yes. Spreads between units and on belongings. A NSPIRE deficiency in assisted housing, and the subject of HUD guidance for HUD multifamily properties.
What to do: Confirm identification from a specimen or clear photo. Inspect neighboring units. Professional treatment (heat, steam, vacuuming and targeted products), resident preparation with help offered, and follow-up until no evidence is found. Keep a bed bug incident record.
Who handles it: Pro. Resident reports early, prepares, and does not move furniture out without asking.
Protected?: No.

Bed bug look-alikes: bat bugs and swallow bugs Cimex spp. (bat bug); Oeciacus spp. (swallow bug) Watch it

How to recognize it: Look almost exactly like bed bugs; telling them apart takes magnification and a trained eye. Found near bat roosts or swallow nests in attics, eaves and walls.
Does it matter?: Yes, because the fix is different: treating a unit for bed bugs will not solve a bat bug problem coming from a roost in the wall.
What to do: Get an expert identification. If confirmed, address the bats or birds (see those entries) and then the bugs.
Who handles it: Pro and owner.
Protected?: The bugs are not; the bats and birds may be.

House mouse Mus musculus Act on it

How to recognize it: Small (body about 3 inches), gray-brown, large ears. Droppings about 1/4 inch, pointed. Signs: droppings, gnawing, grease marks, nests of shredded paper or insulation.
Does it matter?: Yes. Contaminates food and surfaces with droppings and urine, damages wiring and insulation, and enters through very small gaps. A NSPIRE deficiency in assisted housing.
What to do: Find and seal entry points, remove food and clutter, trap indoors, and use secured, tamper-resistant bait stations outdoors where the program calls for them. Clean droppings wet with disinfectant, never by sweeping dry.
Who handles it: Owner (exclusion, exterior program) and pro. Resident stores food sealed and reports holes.
Protected?: No.

Norway rat Rattus norvegicus Act on it

How to recognize it: Large (body 7 to 10 inches), brown, blunt nose, small ears, tail shorter than body. Burrows along foundations, under slabs and in trash enclosures. Droppings about 3/4 inch, blunt.
Does it matter?: Yes. A live rat inside a unit or a building is a Severe NSPIRE deficiency with a 24-hour correction time in public housing and HUD multifamily housing; in voucher units it is a Fail with 30 days to correct.
What to do: Fix trash enclosure sanitation and dumpster lids, close burrows and entry points, and run a professional exterior program. Inside, traps and immediate exclusion work.
Who handles it: Owner and pro.
Protected?: No.

Western black widow Latrodectus hesperus Watch it

How to recognize it: Glossy black female with a red hourglass under the abdomen; irregular, strong web low to the ground in protected corners, window wells, meter boxes, under steps and in garages.
Does it matter?: A bite can need medical care. Common around Wasatch Front buildings; rarely in living space.
What to do: Remove webs and spiders where people reach (doorways, play areas, mailboxes, window wells); reduce clutter and lighting that draws prey. Treat where people are likely to contact them.
Who handles it: Owner and maintenance for common areas and exteriors; pro for treatment.
Protected?: No.

Common house spiders (cellar spiders, funnel weavers) Pholcidae; Agelenidae Leave it

How to recognize it: Cellar spiders: long thin legs, loose webs in corners. Funnel weavers: brown, sheet web with a funnel retreat in shrubs, window wells and basements.
Does it matter?: Rarely. They eat other insects. Large numbers point to an insect food supply or moisture.
What to do: Vacuum webs; fix the lighting, clutter and moisture that bring their prey.
Who handles it: Resident and maintenance.
Protected?: No.

Ants (pavement ant, odorous house ant) Tetramorium immigrans; Tapinoma sessile Watch it

How to recognize it: Small brown to black ants trailing along edges, often after spring rain or in kitchens. Odorous house ants smell like rotten coconut when crushed.
Does it matter?: A nuisance in food areas; not a disease concern. Indoor trails usually come from a colony outside or in a wall void.
What to do: Find where the trail enters; clean food sources; seal entry; use professional baits rather than sprays, because spraying some species can split colonies and make the problem worse.
Who handles it: Pro for baiting; resident keeps food sealed.
Protected?: No.

Yellowjackets and paper wasps Vespula spp.; Polistes spp. Act on it

How to recognize it: Yellowjackets: yellow and black, nest in the ground or in wall voids, aggressive near food in late summer. Paper wasps: longer legs, open umbrella-shaped nests under eaves and railings.
Does it matter?: Stings, and serious reactions in allergic people. A nest by a door, walkway or play area should be handled. Evidence of other pests under NSPIRE.
What to do: Professional removal of nests near people; keep trash and recycling lids closed. Do not seal a wall-void nest from the outside while it is active; the wasps may chew inward.
Who handles it: Pro.
Protected?: No. (Honey bees are a different case; call a beekeeper or pro before removing a swarm.)

Boxelder bugs Boisea trivittata Leave it

How to recognize it: About 1/2 inch, black with red-orange lines; cluster on sunny south and west walls in fall, then wander indoors in winter and spring.
Does it matter?: Nuisance only. They do not breed indoors, bite people or damage structures.
What to do: Seal gaps around windows, siding and vents before fall; vacuum strays indoors.
Who handles it: Owner and maintenance (sealing); resident (vacuuming).
Protected?: No.

Cluster flies and house flies Pollenia spp.; Musca domestica Watch it

How to recognize it: Cluster flies: sluggish, gather at upper-floor windows in fall and late winter after overwintering in walls and attics. House flies: breed in garbage and animal waste.
Does it matter?: Cluster flies are a nuisance. House flies indoors in numbers point to a breeding source in garbage.
What to do: Cluster flies: seal the attic and siding gaps they enter through. House flies: find and remove the breeding source (trash, dumpster, pet waste).
Who handles it: Owner and maintenance.
Protected?: No.

Drain flies (moth flies) Psychodidae Act on it

How to recognize it: Tiny, fuzzy, moth-like flies resting on bathroom and kitchen walls near drains.
Does it matter?: A sign of organic film in a drain, floor drain or sewer leak. They will not go away until the source is cleaned.
What to do: Scrub the inside of the drain mechanically to remove the film, then flush with boiling water where the plumbing allows. Spray adult flies with a strong solution of soapy water. Vinegar traps do not keep up with the population and are not a fix. If flies return, look for a broken drain line.
Who handles it: Maintenance and resident; pro if the source is hidden.
Protected?: No.

Fruit flies Drosophila spp. Watch it

How to recognize it: Small tan flies with red eyes around fruit, recycling and drains.
Does it matter?: A nuisance pointing to fermenting food.
What to do: Remove overripe produce and rinse recycling; clean the source.
Who handles it: Resident.
Protected?: No.

Stored-product pests (pantry moths and beetles) Plodia interpunctella; various beetles Watch it

How to recognize it: Small moths flying in kitchens at night; webbing or small beetles in flour, cereal, pet food, birdseed or spices.
Does it matter?: Contaminate food; do not bite or spread between units the way cockroaches do.
What to do: Find and discard the infested package; clean the shelf; store dry goods in sealed hard containers. Pesticides are not the fix.
Who handles it: Resident.
Protected?: No.

Carpet beetles Dermestidae Watch it

How to recognize it: Small round beetles (adults) and fuzzy, banded larvae; larvae shed skins that are sometimes mistaken for bed bug signs.
Does it matter?: Damage wool, feathers and stored fabrics. Their skins are often confused with bed bug evidence, so get an identification.
What to do: Vacuum edges and closets; clean stored wool and feather items.
Who handles it: Resident; pro for identification.
Protected?: No.

Pigeons, house sparrows and European starlings Columba livia; Passer domesticus; Sturnus vulgaris Act on it

How to recognize it: Nesting on ledges, signs, light fixtures, balconies and in vents and soffits.
Does it matter?: Droppings foul walkways and balconies; nests block vents and can bring in mites.
What to do: Exclusion (netting, spikes, vent screens), sanitation and cleanup with proper protection. Birds must be identified to species first, because most native birds are protected by federal law and cannot be disturbed while nesting.
Who handles it: Owner and pro.
Protected?: These three non-native species are not protected under the federal Migratory Bird Treaty Act; most native birds are. Identify before acting.

Bats Chiroptera Act on it

How to recognize it: Staining and droppings below roofline gaps, vents or soffits; bats seen leaving at dusk.
Does it matter?: Bats can carry rabies. Any bat found inside a living space where it may have contacted a person should be reported to the local health department.
What to do: Do not trap or kill. Use exclusion that lets bats leave and not return, timed to avoid trapping flightless young. Check Utah Division of Wildlife Resources rules first.
Who handles it: Owner and a qualified pro.
Protected?: Wildlife rules apply; check with the Utah Division of Wildlife Resources before any work.

Not on this list?

Text a clear photo to (801) 477-0223 for a same-day identification by a Board Certified Entomologist.

Wasatch Front Multifamily Pest Field Guide · multifamilypestreference.org · Version 1.0, October 13, 2026 · Trenton S. Frazer, M.S., BCE #B3413 · General guidance, not legal advice.