I certainly didn’t mean to come across as a know-it-all but I’m getting the idea it might have been perceived that way and if so, I apologize. I was sharing some information I thought might be helpful and mentioned my dad was an entomologist to let people know I wasn’t pulling the information out of the air. My Dad WAS quite a respected entomologist who was, for many years, the Head of the Entomology Department at the University of Georgia. This was some time ago so perhaps my memory is rusty on some things. He was of the old school that thought insecticides were magic. I was seven when Rachel Carson’s Silent Spring was published and caused much angst among the pro-insecticide entomologists. Some of ya’ll may be old enough to remember her book that preached about the devastation of American wildlife due to DDT. My Dad declared that if DDT were banned we would have mosquitos the size of sparrows and everyone would get malaria! Of course, that hasn’t happened and, because it was banned, we still have Bald Eagles and Peregrine Falcons. It is still in use in Mexico, though.
I agree that the big American cockroaches (which I, too, know as Palmetto Bugs and, in my area, we call them Wood Roaches which is similar to Tree Roaches) will be perceived by guests as horrible – that’s how I feel about them. I meant that, generally, seeing one of two inside is not a sign of infestation since their normal habitat is outdoors – it isn’t impossible, roaches are hardy critters. That is also the only roach that I indicated liked damp, wet conditions–it can survive in dry conditions. However, with the German cockroach, if you see one, you can be sure there are more and should, at a minimum, investigate further. Immediate action should be effective in a short time but they aren’t one that you want to ignore as they reproduce faster than any of the other roaches.
As for the American Roach, I did some reading and I don’t know how it got to Spain but, apparently, it is now considered native there. It is postulated that the American Roach came to American on board ships from Africa.
And there are many types of roaches in America, some that prefer dry, hot weather. There is even a Desert Roach which challenges the American Roach in size.
When I mentioned crumbs or bits of food, I was speaking of the places where there is 1/8th inch or less – perhaps between a stove or refrigerator and built in cabinets or counters. Perhaps you have a thin piece of metal you run down in these spaces and push out anything that falls into them. I don’t and I still don’t have a problem with cockroaches. However, “if I was having trouble getting rid of them”, those would be areas that I could consider as possible problems. But, as “muddy” says, they can live on a lot of things besides human food – they can even go a month without food and water. They will eat any type of fresh or spoiled food, decaying wood and bodies, even hair, books and adhesive such as that found on envelopes.
And, while they may come flying in when guests have doors open they are more likely to come in through cracks and crevices so another thing to do if you are having problems is to be sure all of those little spaces are sealed up – difficult to do in some homes, like mine, which was built in 1955.
Again, I had hoped to be sharing some information that would be helpful. I apologize if I somehow offended.
J
You didn’t offend anyone, no need to apologise!
There you go, ended up in Spain the same way they ended up in America.
Every day’s a school day 
JF
We had to go full on postal as it was an infestation - thanks to our “lovely” neighbor.
While waiting for this great product to arrive, we did use beer traps. But, we made a far bigger dent using flashlight and scissors. About 200 slugs by day 2. Then 20-30 each night thereafter.
I spray diatomaceous earth and boric acid powder into the cracks.
When I had the upstairs as an apartment I knew where tenants were coming from because I ask for landlord references on applications. We had 2 older buildings in town where the exterminators just drove the roaches (and now bedbugs) from floor to floor but never exterminated them.
I told folks moving from those buildings that they could not bring any open bags or containers of flour, grains, sugar, or other dry food ingredients, and that they had to wash and dry all clothing and linens and dry them at high temp before they moved them into the house.
I’ve never seen a roach here. I hope I never do.
I have had a few palmetto bugs and snooty guests. My word we live in Florida there will be a few bugs here or there always! Of course they claimed the roach crawled on them while sleeping. I have house exterminated routinely and if you see a bug it is dead. They spray inside and outside so if one shows inside its dead. Of course they shared this with the 3 other rooms and all wanted a refund except for one lovely girl named Summer. She said we live in Florida what a bunch of sissy the men were and making up stories of live roaches crawling all over. ! Ironically it was 3 men who requested refund. I did refund them. The girl was happy to have whole house to herself. She never saw a bug ever. Funny what people will do for a free night stay.
Well my hats off to you if you pull the stove out at every turnover, I pull it out about once a month and I thought that was often. There is always something to clean when I pull it out.
RR
We pull it out at every turnover too. I don’t want a guest dropping something and then seeing someone else’s macaroni under there or something. Seriously, it only takes about 30 seconds. And another 30 seconds for the fridge.
Well, y’all can face punch me. Finally pulled out the combo washer dryer to vacuum the dust bunnies and found a check dated July 2019 some unfortunate guest had dropped.
In my own apartment, and in one of the rentals, I don’t need to pull out the stove every time because if I take out the warming drawer, there’s no surface under it. All I need then is the torch on my phone and the long long crevice thingy on the Dyson and get every bit of stuff up.
The cooker in the other apartment doesn’t have that but it’s light and easy to pull out.