German cockroaches are the most common cockroach in Pennsylvania buildings, according to Penn State Extension. They are drawn to moisture, grease and cracks, and in apartments they travel between units through pipe chases, shared walls and kitchen plumbing, so one unit's problem often reaches the next.
Key takeaways
- German cockroaches are the most common cockroach in Pennsylvania buildings, according to Penn State Extension.
- Moisture, grease and clutter keep them in a kitchen or bathroom, and removing those matters as much as any treatment.
- Pipe chases, shared walls and kitchen plumbing let them move from one apartment to the next.
- Seeing one roach in daylight often means many more are out of sight, because crowded populations push insects into the open.
- Reliable control is inspection, sanitation, treatment placed in hiding spots and follow-up checks, and in an apartment building it often needs the whole building.
What makes an apartment suitable for German cockroaches?
German cockroaches need warmth, water and food, and apartments supply all three, especially in kitchens and bathrooms. Dense buildings with shared walls and plumbing give them a way to move between units without crossing open ground.
Penn State Extension notes that German cockroaches are drawn to moisture, grease and cracks. A kitchen with a slow drip under the sink, a dishwasher that leaks, a range hood coated in grease and a crack behind the cabinet is a complete habitat. Bathrooms with humid air and a damp floor drain are a second favored area.
Older apartment buildings in Philadelphia often have plaster walls, gaps around plumbing and cabinets fitted tightly against the wall. Those spaces are where cockroaches hide during the day, and where a technician will look first. A kitchen that looks clean on the surface can still hold a population behind the appliances.
Penn State Extension lists only four cockroach species as common in Pennsylvania structures: German, brown-banded, Oriental and American. The German cockroach is the most common of them in the state's buildings, which is why a kitchen roach in a rental is usually a German cockroach rather than a species that needs a different approach.
How can I tell an infestation from a stray roach?
One cockroach is not proof of an infestation, but several sightings in a kitchen at night, droppings that look like ground pepper and egg cases called oothecae point to an established population. German cockroaches are small and tan, with two dark stripes behind the head.
German cockroaches are under an inch long, light brown, and marked with two dark stripes that run back from the head. Adults and young are often found together. Their droppings look like ground pepper or coffee grounds, and they collect in corners, behind appliances and inside cabinets.
Most sightings happen at night or when the lights go off. A roach seen in daylight can mean a large population, because crowding pushes the insects out of their hiding places. The first daylight sighting is worth reporting to the landlord in writing, along with the date and the room.
Check the cabinet under the sink, the space behind the stove, the back of the refrigerator, the cracks around the sink and the gaps where pipes enter. A flashlight and a sheet of white paper are enough to look for droppings, and a photograph helps the technician later.
How do cockroaches move between apartments?
Cockroaches use pipe chases, wall voids, electrical boxes and shared plumbing stacks to move between units. A treatment in one apartment that ignores the neighboring units often sees roaches return from the next one.
A pipe chase is a vertical space that carries plumbing and drains from floor to floor. In older buildings the chase may be open at the bottom or top, and cockroaches use it as a route. A kitchen on one floor can be connected to a bathroom on another without the insects ever crossing a hallway.
Electrical boxes and the gaps around outlets and switches give access to the wall. Roaches can also move through the space between a cabinet and the wall, and around a window frame. These routes are why building-wide coordination matters, and why a single-unit visit often does not end the problem.
A technician may ask to inspect neighboring apartments. This is a practical request rather than a judgment of the neighbors. It changes the job from one unit to a building plan, and that change is what keeps the next apartment from becoming the new source.
What can a tenant do before a technician arrives?
Clean grease and crumbs, store food in sealed containers, fix leaks and empty the trash every night. Those steps remove what the cockroaches need, and they make the technician's inspection quicker and more accurate.
Wipe the stove, the range hood and the top of the refrigerator at least once a week, and clean under the appliances. Grease attracts German cockroaches and helps them survive, so the kitchen is the place to start. Move the toaster, the coffee maker and the bread box so the counter can be cleaned behind them.
Store dry food, pet food and bread in sealed containers. Rinse dishes before they go in the sink and do not leave them out overnight. Empty the trash each evening and keep the lid closed, because a full bin in the kitchen is a dependable food source for a population.
Report leaks and damp areas to the landlord in writing. A dripping trap or a damp wall is a permanent source of water, and a treatment will not last while the moisture continues. Keep copies of your messages, and note the date of each report.
What does a professional program involve?
A proper program starts with inspection, then sanitation and clutter reduction, then treatment placed in hiding spots, and ends with follow-up checks. Integrated pest management, the approach university extension programs describe, combines these steps instead of relying on a single product.
Inspection maps the population: where the roaches are, how many there appear to be and which units they move between. Sticky traps placed in the kitchen, the bathroom and behind appliances are a common way to measure activity over several days, and they show the technician where to focus.
Sanitation and clutter reduction come next, because treatment works better once food and water sources are removed. Technicians often ask the tenant to empty cupboards, move items away from walls and clean grease from appliances, and they explain which steps matter most in that kitchen.
Treatment is placed in cracks, behind appliances, inside cabinets and along pipes, where the insects hide. Gel and bait formulations are common, and the placement matters more than the name of the product. The cockroach control service describes the sequence, and follow-up checks confirm whether the population is falling and where more treatment is needed.
How will you know the treatment is working?
Activity should fall over the weeks after treatment, with fewer sticky-trap catches and fewer sightings at night. A count that stays level after several weeks means the plan needs changing, not that the first visit failed.
Measure progress rather than guessing. Sticky traps left in the same places at the same times give a comparable count from one visit to the next. A technician can record those counts and show you the trend, which is more useful than a judgment based on how often you saw a roach in the last few days.
Expect the first weeks to look messy. Roaches that were hiding can come out as the treatment reaches them, so a short rise in sightings can happen before the numbers fall. Keep the kitchen clean during that time, because food and grease left out will slow the drop and prolong the program.
If the counts do not fall after the agreed follow-up visits, ask what the next step is in writing. It may mean treating a neighboring unit, changing the method in a particular room or looking for a moisture source that was missed. A plan that adjusts to the evidence is the right sign, and a plan that repeats the same visit without change is not.
Why do building-wide plans work better?
A building-wide plan treats the units that share walls and plumbing at the same time, which stops a population from moving back. Coordination with the landlord or property manager is the difference between a one-off visit and a result that lasts.
A single apartment treated alone often sees roaches return from a neighboring unit that was not treated. A building plan treats the adjacent units together and sets a schedule of follow-up checks across all of them. That is more work on paper, and it is far less work over the year.
The lease and the building's management decide who arranges access and who pays for the work, and that should be settled in writing before anything starts. Read the lease for clauses about pests, repairs and access. The city's Licenses and Inspections office can answer questions about housing conditions if the answer is unclear.
Keep a log of treatment dates, what was done and any new sightings. The log shows whether the program is working and gives you something specific to point to if the problem continues. The apartment pest control service is built around that kind of plan.
Frequently asked questions
Why do I see German cockroaches in a clean apartment?
Cleanliness helps but does not stop cockroaches moving in from a neighboring unit or hiding in a building's voids. The usual cause is access through shared plumbing or walls, which a clean kitchen cannot prevent alone.
Do sprays work on German cockroaches?
Sprays can knock down visible roaches, but they rarely reach the places where the population hides, and they can push roaches deeper into the wall. Placing treatment in the hiding spots is what makes a program last.
Are cockroaches a health problem?
Cockroaches can contaminate food surfaces and are associated with allergens, which is one reason an infestation should be addressed rather than ignored. Ask the technician about the specific risk in your home, especially if someone in the household has asthma or allergies.
How long does a cockroach program take?
A program usually runs through several visits and checks, because the population has to be reduced over more than one life cycle. The technician sets the schedule after inspection, and you can ask how many follow-up visits are expected before you agree to start.
Should I move out if I see roaches?
Not necessarily. Many tenants stay while a program runs. Clear the kitchen, keep food sealed and ask for a written plan. If the landlord does not respond, a legal aid group or the city's Licenses and Inspections office can advise you on your options.
Sources
This guide is general information for Philadelphia County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.