I did a little research & it seems the anticoagulant injected when they bite is what causes the itching/swelling just like with mosquitoes. I would imagine there's a good chance the anticoagulant is a protein & so the ammonia would work. At least it's worth an experiment! And let us know if it works for you.
Thought you might be interested in these 2 articles:
http://entnemdept.ufl.edu/crea...
This one shows some trapping devices
http://entnemdept.ifas.ufl.edu...
