I doubt very much that you have mites from the little that you've told us. Biting mites can only live a couple weeks without a host (that'd be a living blood bearing source, not a fabric stash) and you said you're only bitten in the summer months. One doctor said insect bites (mites are not insects, btw), another said an allergy. You really don't have a good idea of what's causing what you assume are bites.

Ask yourself some questions to try and narrow it down. Do you have pets? Are there mice in your house or nesting nearby? Are other members of your family suffering the same skin irritation? Does it only happen in your sewing area? Do you have to come in direct contact with the fabric to have the irritation occur? Do you open the windows in the summer? Does dust and pollen blow in? Do you have any known allergies? Sensitive skin issues? If your doctors didn't ask things like that, they should have. Don't just assume mites are the cause...it could easily prevent you from finding a real solution.

I would not starch any fabric before I stash it. Mites and those little wormy things really like the taste I think. Had a friend who did it so would be ready for the project. She had to do a lot of washing and they can do damage. I really have not had any problem in the many years I have been stashing so am no expert on this.

How do you know you have mites? (Not being a smarty pants here, I'm just wondering). I am familiar with mites on plants but never realized it was a problem with quilting fabric. Scary thought here.

I have never heard of mites in cotton fabric, I don't prewash but I've never had a problem. I don't have any pet either, you didnt say if you do.

I'm the same way, my DH doesn't understand why I'm the only one who gets these welts and itches.

Have either of those dermatologists tested you for your reaction to formaldehyde? Skin irritation is a common symptom of low level exposure.

Why don't you try just a regular prewashing of at least some of your fabric before storage, not for bugs but for chemicals. Store that group separately (but in the same room) and see if, over time, you have the same reaction.

We do have cats. one which sleeps on my fabric, I've talked to the local Vet's office, and they told me we DO have fleas in this area, so I bought Frontline from the office, applied the solution on the cats and was told to get a flea collar, put it in the bag of my vacuume cleaner and vacuume, it will pick up what flea stuff is in the carpet and kill it.
Im also trying the Dawn in water with a light over it. Hope all this works.

Mites
 

I thought I had some type of bug when I was first diagnosed with Rheumatiod Arthritis. I went to my Priimary Care Dr. who did not investigate my complaint of itching and rash but gave me a RX for lice. This went on for almost 8 mo til I learned more about RA and found out I can have itching and rashes. It didn't go away from all the Dr. treatments and drove me up a wall. I even went to my local extension service and hd everything I brought looked at. Nothing was there. I washed everything, shampooed, vaccuumed etc. Exterminators said I coul be allegeric to something. When I read more abut RA and talked wit my specialist, I then learned it was from the disease and learned to calm down whenever I felt that way. One thing for me is when I would scratch the itch, it would hurt instead of releiving it. I got rid of that Primary Care Dr. as she did not understand RA nor did anything but write scripts. So she had reinforced my fears of having bugs.
Take a sample of your fabric to your extension service to look at under a microscope to see if it has mites and treat accordingly to their advice.

I have. There are mites in some of my clothing. They hide inside the seams. You can tell by a slight discoloration of a rust-like color. Borax and amonia sometimes do the trick but other more infested clothing is tossed. What really is alarming, I have gone out and bought new clothes and guess what? You guessed it. mites had infested the seams.

mites or bedbugs?