Would it annoy me? Probably not, but I always tell all my guests "Help yourself!"

You have to ask yourself why you are getting annoyed. Is it because they're eating anything and everything and it is financially taxing? Are they eating a meal you had been anticipating eating? Or is it that they aren't asking and just presume its ok?

If I had to guess, you are feeling a little annoyed because more than likely, you know its good manners to ask someone before you go rummaging through your cabinets. But, lets be honest -- did you ask every time you rummaged through the cabinets when you were growing up and in their home?

I will say, I had a similar scenario but not with a parent -- instead a new boyfriend. He was at my house and we had been dating and become comfortable and the first time he started going through my things I felt a little irritated. Aren't you going to ask?! But, I quickly realized it had nothing to do with WHAT he was doing and instead with HOW it was making me feel.

The question is this -- do you want to let this bother you while they visit or can you come to terms with the fact that it is probably something they're doing without even realizing it. You can either confront them and maybe raise conflict or you can accept it, embrace it, and move on.

Maybe if you want to gently broach the topic, something like "Hey, I wanted to see if you had any requests for meals, snacks, etc. when you come over so I can have it ready for you."

That way, YOU acknowledge you know they're going to eat and then they acknowledge they will be mooching and everyone wins?

Although, when my sister visits I ask her, she says "I don't want anything" then she eats the last of my favorite ice cream. So, I think this might just be a right of passage for some families.

Good luck!!! Sometimes, WEIRD things annoy us. There is no rationale. You need to examine what might be triggering your response. That might lead to some relief.