Roach-Proofing a Desert Kitchen

German roaches do not need much. A slow drip under the sink and crumbs behind the toe kick will hold a population indefinitely. In a desert city, water is the limiting factor — which is good news, because water is the easiest thing to take away.

Water first, always

Before you touch a crumb, dry the kitchen out. Check the trap under the sink, the dishwasher door seal, the fridge drip tray, and the line to the ice maker. A roach can go weeks without food and only days without water; removing moisture is the single highest-value thing you can do.

The ten-minute weekly reset

• Pull the toe kick panel or vacuum under it — that gap is the number one German roach harbourage in a kitchen.
• Wipe under and behind the toaster, kettle, and microwave, where grease film builds up unnoticed.
• Empty and rinse the recycling bin, not just the rubbish bin. Sticky cans and bottles are a reliable food source.
• Dry the sink completely last thing at night and wipe the draining board.
• Check the fridge drip tray monthly — it is standing water in a warm, dark, undisturbed spot.

Stop bringing them in

German roaches rarely walk in from outside in Phoenix. They arrive in cardboard, grocery boxes, second-hand appliances, and moving cartons. Break down and remove cardboard the day it enters the house, and check the motor housing of any used appliance before it comes inside.

Seal the harbourage

Roaches want tight, dark contact on both sides of their body. Caulk the gap between the counter and the splashback, close the void where pipes pass through cabinet backs, and fit escutcheon plates on exposed plumbing. Every gap you close removes a place they can breed.

Why sprays alone disappoint

Over-the-counter aerosols kill what you can see and scatter what you cannot, which pushes the population deeper into voids and wall cavities. Gel bait works with roach behaviour rather than against it — they feed, return to harbourage, and the effect carries through the population. If you are seeing roaches in daylight, the harbourage is already crowded, and that is the point to get a professional inspection rather than another can.

First, work out which roach you are proofing against

This changes everything you are about to do, and it takes ten seconds. Big, rusty-coloured and met at night near a bathroom drain means something that came in from outside and will not set up in your kitchen. Little, pale, quick and seen on a worktop means the species that does breed indoors, and the job changes completely. Our cockroach control page carries the full side-by-side if you want certainty before you start.

For the first kind, this article is the whole answer: close the routes and the problem stops. For the second, everything here still helps but will not finish the job on its own, because you are dealing with a population reproducing behind your cabinets. There is an identification guide here if you are not sure.

The under-sink cabinet, in detail

If you only open one cupboard, open this one. The cabinet under the kitchen sink is the single most productive place in a Phoenix kitchen for cockroaches, and it is usually the least inspected.

Clear it out completely and get a torch in there. You are looking for the holes where the pipes come through the back or the floor of the cabinet. On most homes those are cut oversize with a hole saw and left open, which means the cabinet is directly connected to the wall cavity and, from there, to the rest of the house. Seal them: backer rod pushed into the gap, then sealant over it, or an escutcheon plate if you want it tidy.

While you are in there, check for damp. A slow drip from a supply line or a waste connection is both a water source and a sign of a leak worth fixing anyway. Dry the base, and do not put the cleaning products back on a wet shelf. Roaches need water more urgently than food, and this cabinet often supplies both.

Where they actually live in a kitchen

Cockroaches spend most of their time pressed into a tight, warm, dark space. When people say they have sprayed the kitchen and it did not work, this is usually why: the spray went on open surfaces and the roaches are in none of them.

• The motor compartment of the fridge. Warm, dark, undisturbed, and often with a drip tray of water underneath. Pull the fridge out and vacuum the coils and the floor behind it.
• Under and behind the dishwasher. Warm and damp, with a gap along the toe kick that leads into the cabinet run.
• The gap beside the cooker. The few millimetres between the appliance and the cabinet collects grease and crumbs and is almost impossible to clean without moving it.
• The toe kick. The recessed space under base cabinets is a continuous void along the whole kitchen. Roaches travel it.
• Hinge and shelf-pin holes inside cabinets, and the gap where the cabinet back meets the wall.
• Behind the microwave and inside the housing of any built-in appliance.

Vacuuming these is more useful than spraying them. You are removing insects, eggs, and the food that keeps them there, all at once. Empty the vacuum outside afterwards.

The drain routine

For the big outdoor roaches, this is the fix, and it costs nothing.

Every drain has a U-bend that holds water and seals your room off from the sewer line. In this climate that water goes quickly, and a fitting nobody runs stops being a barrier within weeks — after which it is simply an open pipe into the room. Once a month, send water down everything you do not use: the spare bathroom, the laundry standpipe, the garage floor drain. Where something is genuinely never touched, a little oil floated on the surface buys considerably longer.

A faint sewer smell in an otherwise clean room is the same story. If you have put the water back and the smell or the activity carries on, the fault is in the pipework rather than the room, and that is a plumber’s job before it is anybody else’s.

Storage, cardboard and pet food

The kitchen habits that matter are narrower than general tidiness, and a few specific ones do most of the work.

• Get rid of cardboard. Corrugated cardboard is close to perfect roach habitat: warm, dark, layered, and edible. Boxes stacked in a pantry or a garage against a warm wall are a nursery. Break them down and take them out rather than storing them.
• Decant dry goods. Flour, rice, cereal, pasta and pet food into sealed containers. Paper and thin plastic packaging is not a barrier.
• Lift the pet bowl overnight. Food left down after dark is the most reliable overnight food supply in most kitchens, and it will out-compete any bait you put out.
• Use a bin with a lid, and empty it before bed rather than in the morning.
• Deal with the recycling. Rinsed containers are fine; unrinsed ones sitting in a warm garage are a feeding station.
• Wipe the gap, not just the counter. Grease travels along the underside of the counter edge and down the side of the cooker where nobody wipes.

If you already have German cockroaches

Different situation, and worth being honest about. A German cockroach population is behind the cabinets, not on them, and the females carry their egg cases until nearly hatching, so a treatment that misses the eggs is a delay rather than a solution. About 30 eggs ride in each of those cases, which is the arithmetic behind how quickly a German population rebuilds itself. Three things make it worse, and all three are common:

• Bug bombs. A total-release fogger does not reach into voids and it scatters the population deeper into the structure and, in a shared building, into your neighbours. There is almost no situation where this is the right tool.
• Spraying over bait. Residual spray taints a gel placement and drives them off it, which means each product quietly undoes the other. If you have been spraying, say so before anyone baits.
• Competing food. Bait has to be the best thing on offer in the room or it simply gets ignored. Every point in the section above is really about making the bait the best meal in the room.

At that stage the sensible sequence is: stop spraying, do the cleaning and sealing described here, and get bait placed properly in the voids where they live. More on how cockroach treatment works.

The routine, weekly and monthly

None of this takes long once the first deep pass is done.

• Weekly: wipe the cooker sides and the counter edge undersides, empty the bin at night, lift the pet bowl, check under the sink for damp, and take out any cardboard that has accumulated.
• Monthly: pour water down the unused drains, pull out the fridge and vacuum behind it, and check the seals around the pipe penetrations under the sink.
• Twice a year: pull out the dishwasher and cooker properly, vacuum the toe kick line, and re-check every seal you made.

If you are doing all of this and still seeing them, the source is outside the kitchen — a drain elsewhere in the house, a shared wall, or a route in from the yard that the foundation-line sealing guide covers — and that is worth having someone look at rather than repeating the same cleaning. More Phoenix-specific guides are on the blog.

The bathroom deserves the same pass

Kitchens get the attention, but in Phoenix the bathroom is where most people actually meet a cockroach, and the reasons are slightly different.

• The drains. Same trap rule as the kitchen, and guest bathrooms are the worst offenders because they go weeks without use. Include the shower and the bath, not just the basin.
• Under the vanity. The same oversized pipe holes as the kitchen sink cabinet, and usually the same damp. Seal them the same way.
• Behind and under the toilet. The gap where the closet flange meets the floor is frequently open into the void below, and the base of a toilet is one of the more reliably damp spots in a house.
• The bath access panel. If there is a removable panel at the end of the tub, look behind it. It is dark, damp, undisturbed and connected to the plumbing chase, which makes it close to ideal harbourage.
• Ventilation. A bathroom that does not clear its moisture is supporting roaches, silverfish and everything else that needs humidity. Run the fan longer, or fit one that works.

The garage, the bins and the yard side

The last thing worth doing is stopping the supply, because a kitchen sealed against a yard that is full of cockroaches is a losing position over time.

Outside, the Turkestan cockroach lives in irrigation boxes, water meter boxes, leaf litter and anything stacked on the ground, and the males fly to porch lights on summer evenings. A house that stands empty for part of the year has a version of this problem all its own, because the drain traps dry out and open a route in — the Scottsdale page goes through what that does to a seasonal property. For anything you find and cannot identify, send us a photograph. So the useful changes are: get stored items off the ground and away from the wall, clear leaf litter and dense ground cover back from the foundation, and move outdoor lighting away from the doors you actually use rather than mounting it right above them. Warm-toned LEDs pull in noticeably fewer insects than cool white ones.

Bins matter more than people expect. Keep them lidded, keep them off the wall of the house, and rinse them occasionally — a bin that has had something sticky in the bottom since spring is a permanent food source a few feet from your door. The same applies to recycling stored in a warm garage.

And treat the garage as part of the house rather than as outdoors. It usually has a drain, an open slab-to-wall junction, cardboard storage, a fridge or freezer with a warm motor, and a door into the kitchen. Nearly everything in this article applies to it.

Roach-proofing questions we get asked