Rubbing alcohol is my universal remedy!
So is regular alcohol.... everclear makes a good barter currency / antiseptic / aww to hell with it get drunk...
When the SHTF
Once when my dad and I were on a fishing trip, we were devoured by mosquitoes, right through jeans and long-sleeve shirts. We put Scotch on the bites (cheap stuff, mini-bottles from an airline, remember those days), and it killed the itch completely.