The Pests

German Cockroaches in a Restaurant: How They Arrive, Where They Live, and What Actually Removes Them

Written for: Restaurant owners, kitchen managers, the staff who open and close, and the managers who read a service report

Parts of this page marked Professional synthesis, not law are a Board Certified Entomologist's reading of published records. They are not legal rules, they are not legal advice, and they are written to read the same for an owner, a customer, or either side's counsel.

The German cockroach is the cockroach of commercial kitchens. It does not live outdoors on the Wasatch Front; it lives in buildings, and it moves between them in what people carry. Every live-cockroach line in the county’s inspection record is, as far as this site can tell from the inspectors’ own wording, this species or a near relative (what inspectors cite). This page is what I would tell a manager standing in the kitchen, with the published source for each claim.

How they arrive

They come in with deliveries, boxes and used equipment.

Look for other methods of entry, such as from items being brought into the building, especially appliances, furniture, boxes, and items that were recently in storage. — UC IPM, Pest Notes: Cockroaches

Inspect food deliveries before putting them in kitchens. — UC IPM, Pest Notes: Cockroaches

Inspect incoming shipments of food or products for roaches or egg sacs. — Utah State University Extension, German Cockroach

The Food Code says the same thing as a duty: “Routinely inspecting incoming shipments of FOOD and supplies” is the first item under Controlling Pests (the Food Code page). The Delivery Inspection Card is that duty written on one page for the person who receives the truck. Egg cases are the thing to look for; a single case carries the start of a population:

Look for egg cases glued to undersides of furniture, in refrigerator and other appliance motors, boxes, and other items. Remove any that you find. — UC IPM, Pest Notes: Cockroaches

Where they live

Warm, humid, dark, and close to food and water. In a kitchen that means the motor compartments of reach-ins and ice machines, the void behind the dish machine, the underside of the three-compartment sink, the gap behind the line, and any wall void with a water line in it.

They prefer food preparation areas, kitchens, and bathrooms, favoring warm (70° to 75°F), humid areas that are close to food, water, and dark areas for harborage. — UC IPM, Pest Notes: Cockroaches

Inspect and monitor all areas where food is prepared, stored, or eaten, and where moisture and heat are present. — Utah State University Extension, German Cockroach

Do not keep stock in cardboard: “Do not store items in cardboard boxes long-term” (Utah State University Extension). The corrugations are the kind of warm, dark, tight space the extension sources describe as harborage, with the food still in it.

What removes them

Professional synthesis, not law. The program I write for a kitchen has four parts, and the order matters.

1. Sanitation and harborage. Grease and crumbs under and behind equipment, standing water, cardboard, and the voids where pipes enter walls. Nothing else works well while these remain. The Food Code’s “Eliminating harborage conditions” is this step.

2. Bait, and rotate the product. Gel and station baits are the core treatment in a kitchen because they are placed in cracks and crevices, not sprayed over surfaces. Resistance to bait active ingredients is real and documented, which is why the product is rotated rather than reapplied:

Proposed strategies for managing resistance in B. germanica include rotating between different products or using mixture products with multiple modes of action, rather than using single active ingredient (AI) products with single modes of action. — Fardisi et al. 2019, Scientific Reports

We found that prolonged exposure to baits containing fipronil or indoxacarb increased physiological resistance to these compounds. — Liang, McGill and Pietri 2017, Journal of Economic Entomology

It may be necessary to move bait stations to other locations, use more stations, apply more bait, or consider a different bait product. — UC IPM, Pest Notes: Cockroaches

My own practice is to rotate by the class of active ingredient, not just the brand, so that a population surviving one chemistry meets a different one next. The published support for that is the cross-resistance finding above, in which exposure to one bait raised resistance to another; the papers say “different products,” and the class rule is my reading of why.

3. Monitors that prove the kill. Sticky monitors placed before treatment and read after it are the only honest measure of whether the program is working. A kitchen with no monitors has a technician’s opinion; a kitchen with monitors has a count.

To evaluate success, keep records of cockroaches trapped in different locations before and after you start your management efforts. — UC IPM, Pest Notes: Cockroaches

Use cockroach traps to determine infestation level, harborage location, movement and control success. — Utah State University Extension, German Cockroach

The monitor counts belong in the Records Binder; they are also the evidence an inspector, an insurer or a lawyer would ask for (records that hold up).

4. Clean up the droppings and the dead. This is part of control, not housekeeping after it. The droppings carry an aggregation pheromone that draws cockroaches back to the same spot; the cadavers and skins are an allergen; and under the Food Code, dead and trapped pests that accumulate are a citation of their own (dead pests count).

Vacuuming also removes cockroaches, shed skins, and egg cases, reducing overall cockroach numbers. — UC IPM, Pest Notes: Cockroaches

These deposits contain a natural attractant or aggregation pheromone. — UC IPM, Pest Notes: Cockroaches

Because aerosolized bits of shed skins and droppings of cockroaches may cause allergies when inhaled, it is recommended that the vacuum cleaner have a high efficiency particulate absorber (HEPA) filter or triple filters. — UC IPM, Pest Notes: Cockroaches

What is not on this list is a store-bought aerosol. It does not reach the harborage, it is not labeled for a food establishment, and it is a critical citation in a kitchen (who may apply pesticide).

Cockroaches and Salmonella: what the research shows

This is the part managers ask about, and it is the part where the most gets said that the papers do not support. What follows is stated only as far as the published work goes.

Research shows that Salmonella can multiply inside German cockroaches and leave in their droppings, so droppings and dead cockroaches are a hazard, not only live insects. In laboratory work, the bacteria persisted in the insect’s gut and were shed in feces:

Typhimurium), these bacteria replicate in the gut, reaching a steady state and persisting for at least 7 days without eliciting pathogenesis (11, 12). — Turner, Van Hulzen and Pietri 2023, Microbiology Spectrum

In these experiments, the feces deposited at the harborage site by infected donors were again always positive for S. — Mond and Pietri 2023, Ecology and Evolution

Cockroaches that never touched the original source can pick up Salmonella by eating droppings and dead cockroaches, which can keep a colony infected:

Furthermore, we provide definitive evidence that coprophagy and necrophagy are routes of transmission but could not exclude sharing of food or water as contributing routes. — Mond and Pietri 2023, Ecology and Evolution

And the same authors draw the conclusion this page’s fourth step rests on:

Although the relative importance of horizontal transmission of pathogens in cockroaches in the field remains to be determined, these results also highlight the important role that food and water sources in the local environment may play in cockroach‐borne pathogen transmission and emphasize the importance of sanitation for not only abating infestations but also mitigating pathogen transmission. — Mond and Pietri 2023, Ecology and Evolution

Repeated exposure to the same bait builds resistance, and in some laboratory strains, bait survivors were more easily infected with Salmonella. That is one more reason the program confirms kills with monitors instead of reapplying the same product:

Our results show that a sublethal exposure to bait containing the common insecticide indoxacarb can increase susceptibility to subsequent infection by ingested S. — Van Hulzen and Pietri 2025, ACS Infectious Diseases

Interestingly, increased susceptibility to infection after sublethal bait exposure was cockroach strain dependent and did not increase the rate of shedding of the pathogen in excreta. — Van Hulzen and Pietri 2025, ACS Infectious Diseases

What this site will not say: that any share of food poisoning is caused by cockroaches, that cockroaches spread antibiotic-resistant Salmonella, or that baiting makes cockroaches better vectors. None of those is in the papers. The work above is on the German cockroach; it is not applied here to American or oriental cockroaches.

If you have them today

Call your pest company today and ask for monitors, bait placement and a return date, and ask what product class was used so the next visit can rotate it (questions to ask). Put the delivery card at the back door. Assign the morning sweep for cadavers. Write the date on the service report. Text me a photo if you are not sure what you are looking at: (801) 477-0223.