Ok, I think I have answered my own question....found this on the bath protocol
2. ACTIVATE MMS IN A CUP OR GLASS before adding to the tub water. Place 30 drops of MMS in a cup. Add 2.5 teaspoons of lemon juice or citric acid (150 drops). Plan for a 20 to 30 minute minute tub sitting. If you have open skin sores or severe body wounds, consider reducing the MMS to 20 drops mixed with 100 drops of citric acid or lemon juice (1.5 teaspoons) so that sensations of heat or burning will be reduced. Open sores usually heal quickly due to the disinfecting action of MMS. The 1 to 5 ratio is the normal MMS protocol.
So I conclude re; open sores from insect bits,that either bathing or spraying will work and if bathing reduce to 20 drops MMS and 20 drops of the 50% Citric Acid solution