My name is ***** ***** I will be happy to help you.
I'm so sorry you've been experiencing this problem for so long; I can only imagine your frustration.
From your description, it is my opinion that yes, the mice are breeding and that's why you're seeing more or seeing them at all, and yes, they are mostly the same mice. If the poisons put down by you and the professional exterminator are guaranteed to kill the mice, there's not reason this shouldn't be happening, unless the poison is not strong enough. They may be immune to it, if it's been used for a long time, to get rid of mice, and they may be rejecting the wheat based one, because they don't like the taste or they can smell that it is dangerous to them.
The rodenticides that are used in the U.S. can contain different types of poisons. Some work faster than others. Here is additional information about how these rodenticides work.
The bromadiolone based poisons you're using should be causing internal hemorrhaging and killing the mice, but as you can see, at the link above, this is a lengthy process and that may be why, as you suspect, you're seeing the same mice over a period of time. As you can read in the link above, there are faster ways to kill the mice in as little as 2 days. Try to find the rodenticides that kill more quickly, in your area or ask the exterminator to get it (perhaps use a different exterminator).
Instead of cotton wool, stuffing any cracks/openings with steel wool (like 'Brillo' soap pads for washing dishes/pots, but without the soap) is more effective, as the mice can't get through the tangle of steel wool.
Make sure no food or trash is left out on counters or in the house and constantly vacuum the floors to get rid of crumbs. For foods in your cupboards, in boxes, either refrigerate them or put them in plastic ziploc bags, so the cardboard can't be chewed at to get to the food.
The most important thing now, is to find where they are coming in and if they are living in the walls, a stronger approach by an experienced exterminator who deals with mice, will be necessary.
I wish you much good luck and hope over a short period of time, you will finally be rid of this problem and take precautions so it doesn't happen again!
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Sorry I have been offline today. Please give me some more time to read the information in the link you have provided. I believe that mice sometimes avoid traps, but they can help to get rid of some when poisons do not fully control the infestation. Is it also possible that the mice are competing for the same source of food, leaving some of them untreated? I do try to put the food in various places. What is the typical life span of a mouse if they live long enough to breed?
No problem; read the information and let me know what you think.
If you put out quite a few trays of bait (poison) in locations of great activity, they should all eat the poison.
The typical lifespan of a 'house mouse' is about 2-3 years. Technically, they can breed as early as 4 weeks of age, but this usually ends up being not good for the health of the mother and the babies; however, those that survive will continue to breed and this is part of the problem of an infestation.
You can use traps, if you like (I don't believe in them), but as you said, experienced mice learn to avoid them. I'm a pet lover and know these are not your pets, but any mode of getting rid of them involve killing and it's not a quick death.
The main thing is to survey the outside and inside of your home and determine where they're getting in, so you can seal up those areas with cement, caulking or steel wool, as I mentioned yesterday. If they're living in the walls, an experienced exterminator can place poison inside the walls and this might help dispose of them more quickly.
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