The microwave is filled with oil and vaporized food particles that have penetrated it entirely. This is a very enjoyable place for cockroaches to live as it has an excellent food source, they do not live in the part of the microwave that food goes into, they live in the back, away from the microwaves themselves and in the warmth of the electronics. While it tends not to have water it is generally in the kitchen and the kitchen is where most cockroaches go to find water. Any leaky pipes or drains, faucets, and anything else that can provide a large amount of water to cockroaches. They will often live under the base of the bottom cupboards and access the kitchen’s various utilities late in the night.
If you are dealing with a cockroach infestation or have suspicions thereof, contact Shuswap Cockroach Control for a fast and effective complete eradication.
The best thing you can do is throw the microwave away and buy a new one. That will get rid of the cockroaches living inside of it. You can try cleaning it with bleach but opening the microwave from the back is illegal in most countries. If you have cockroaches in your microwave you likely have them everywhere else as well. In this case, trying to clean with bleach will have little effect. Cleaning does not get rid of cockroaches. They hide in cracks during the day and are not bothered by most cleaning chemicals aside from boric acid or silica. There are methods of killing them off but it will take months and you will never truly be free of them.
There are domestic options for a small cockroach infestation, they are not effective for a full infestation but can help limit and control the infestation. Some baits can draw cockroaches into eating them and getting poisoned, there are sprays you can buy that will kill them when you spray them directly and many other kinds of traps and baits that can work in a small scale infestation. However, if you are seeing cockroaches daily and more than the one you have a large infestation and domestic products will not do.
The best way to get rid of cockroaches is to call a professional and licensed exterminator who can come to your home and perform a commercial cockroach treatment that will effectively end your cockroach issue. They will do a crack and crevice treatment to poison the opening they like to live in, a baseboard spray treatment to limit their mobility, and something called a ULV or an ultra-low volume mist that will fill hard to reach areas.