I had one get inside mine. I know this sounds awful, and I'm not a dirty person, but in some areas you just can't get away from them, you just have to do what you can to keep them under control. Anyway, I knew he was in there because I could see him crawling around the LED light where the clock is. I refused to use it and was going to toss the whole machine even though we had only had it a week or so.
But instead I came up with something to try. First I unplugged mine and removed everything removable (those I ran through the dishwasher), and then I took a bug bomb and set it inside. Before I turned it on tho, I took a good sturdy trash bag (the big black kind) and put the microwave inside it and got it ready to be tied closed. Then I put all that inside another big black bag just to be sure it was enclosed good. Then I reached in and quickly turned the bug bomb on and closed the microwave door, then quickly tied each bag up good. I let this sit for 24 hours before opening the bag.
Once I opened it and took the microwave out and tossed the bags and the can in the trash outside, I left the microwave sitting with the door open for 12 hours. Then I took hot hot soapy water and washed it down good inside and out. I let it completely dry for 4 hours before plugging it in again. Then I took a large plastic bowl and filled it with water and put it in the microwave and cooked it to a boil. I brought that out, put fresh water in the bowl and did it again. I did this 5 times each time using fresh water.
I did this 2 years ago and have been using the microwave ever since and never had another problem.
By Cricket from Parkton, NC