Aspergers 6 year old

Very common, yes, almost ubiquitous.

It's actually good for him, it's something to focus on.  Stopping doing it might actually be bad for his school work as he won't be able to concentrate as well.  All you can do is get him something else to fiddle with that it doesn't matter if he breaks it, like a dog with a chew toy!  That generally does work.  All kids (and adults) have different "tastes" in things to fiddle with, though, so you may need to experiment a bit to find something he likes mangling better than his shirt!  At least he seems to understand why he does it, so it might not be too difficult to get him to fiddle with something else instead.

It's not totally alien to non-autistic people, actually - everybody knows how some people fiddle with things when they're nervous.   You hear the expression, "I'm just doing it for something to do with my hands..."  People with autism tend to be nervous, or at least distracted, a lot of the time, especially in a busy place like a school, because they notice every little thing so their attention is flitting all around the room, every time anything moves, and you can't study like that.  Messing about with something gives you something to focus your attention on and keep it there, and then you can keep everything else steady.

People often never do grow out of that habit, and I remember a conversation on Aspie Village (a UK forum for adults with Asperger's) one time where somebody had found a site selling wooden beads, rings, and other oddities, and several people were discussing treating themselves to some nice things to fiddle with!  :-)

It's probably not meant to be "destructive", it's just that if he's particularly agitated he fiddles with things so hard that he shreds them.  It's easily done, and he's only little.

Don't worry, you'll get the hang of these things, so will he.

As others have highlighted this isn't destructive behaviour. 

You come across as though you are angry at your son, yet he's doing the right thing. Stimming is something that autistic people do to cope with the pressure of living in a world where our needs haven't been thought about when designing environments, such as school. It helps to manage our MH and if your son wasn't allowed to do it could have very serious consequences for his well-being.

In the grand scheme of things surely your son's MH is more important than a bit of cloth and the expense of buying new school wear every month or so? Outside services, such as OT or SENCOs can provide recommendations but all they will be are ideas and they may not specifically work for your son, it's all about trial or error. Stabbing something else like a piece of blue tack might help, some students like fidget toys.

NAS67615 said:

If we ask him to stop, his desire to destroy, pick, break thing overrides everything, even though he knows it’s wrong.

As he's only 6 being able to communicate effectively together re your needs with his school clothes and getting your son to find a suitable stim is likely to be a very slow process. If he's treated in a way that upsets him, such as being told his behaviour is wrong, is will exasperate his need to self-sooth, which is what you are already experiencing. Remember just because you as a PNT think something is wrong, it doesn't mean this is wrong for the autistic way of being.

What are you doing as a family to help your son manage his mental health? As an autistic mum to an autistic daughter, I'm conscious that exercise works wonders for my MH, which is also true for my autistic husband. Although our LO hasn't started school yet I've already got a list of activities, inc junior park run, to try out in order to help her establish life long habits for managing her emotions.  

If i didn't already know I was autistic, I would have realised it from the excitement I got reading this 

It is self stimulating behaviour. As he is undergoing assessment make a note o it in a diary and mention it to the doctors. At school ask for a meeting with the Senco and ask her to refer him to the Occupational Therapist. It is their job to recommend a sensory activity that would be more acceptable. Ask the same from the Paediatrician.Plastic's advice is brilliant.

Hi - There's a good chance that he's stimming - he might be finding things that are so profoundly interesting and stimulating that he literally cannot help it.    They might provide a strange vibration or sound or just be very pleasant when he does it - like a mini science experiment that needs repeating until all of the data has been collected.  

It's often an outlet for stress when the need to override things that are not fitting with his world - a common one at school is seeing bad behaviour in other kids and seeing them get away with it - it causes logic problems that can't be solved in the moment.

I'm not sure you can directly stop what he's doing but you can redirect it by providing millions of other fascinating things for him to explore instead - sacrificial items that he can feel and explore to stimulate his mind.      Things like old clocks to dismantle, (brass cogs feel awesome between the fingers) old gadgets to take apart, torches with kaleidoscopes, different materials to test, cut, rip, poke holes in - canvas, rubber, cotton thin metal etc.      Let him find a place where his brain can do things it likes to balance the stress -  and he'll learn lots of things too.