How do I respond to my mother? She picks at her arms and thinks she sees worms crawling in and out of her arms.

In your profile, you state your mother suffers from dementia/Alzheimer's; seeing bugs and other hallucinations are common with brain disorders, unfortunately. Check out this website for more information:

https://www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/hallucinations

Your mother is obviously experiencing an advanced state of dementia/ALZ and needs help with bathroom hygiene and showering, etc. She definitely WILL get into deep trouble if she's not carefully monitored when using the bathroom, and then washed up properly afterward.

Read up on the subject, watch Teepa Snow videos on YouTube, and contact your mother's doctor for further guidance about what to do next.

Good luck with a difficult situation.

A fall, a UTI, alcohol withdrawal, Low sodium can also cause these type hallucinations. She needs blood work.

It may be an anxiety issue. Meds could be of help if it is.

If your mother believes her arms are crawling with worms and is picking at her skin then she should not be allowed to use a restroom on her own, or do anything else on her own either.
I hope she's not staying alone while you're at work because that is dangerous.
Your mom needs a mental evaluation done in a hospital. If she refuses to leave the house call an ambulance and tell them that she is hurting herself and that you fear for her.
They will take her to the hospital and that will be your starting point to get some help and services for your mom.

Maybe it's not worms as much as maggots. She may be seeing death in someone?

How recently has she been seen by a medical doctor who knows her and hopefully understands her? Has she received a recent test for a UTI?

You state that she has dementia. If so, she may either be experiencing hallucinations or she may believing that she is accurately reporting g to you what is happening to her.

Either way, she needs to be seen by someone who can assess her mental and physical wellness AS SOON AS POSSIBLE.

If she’s refusing to leave the house, contact you municipal board of health and see if she can be seen by a Visiting Nurse.

Does she stay by herself when you’re at work? She may not be safe if no one is with her. Have you considered what you will need to provide for her when her behavior deteriorates farther?

Hope some solutions will be available to you soon!