You can buy little pieces perfect for doing bug jars from the above posted site:
http://www.bugfabric.com
I found this out after searching the local fabric shops and finding practically nothing but butterfly fabrics. Then checked out the above webstore. They sell pieces in correct size in groups for one quilt. I spent more on a handful of butterfly fabrics and so wish I had looked at www.bugfabric.com first.
Good luck,
Kat