I have used the blue can (flying insects} for years to kill ants and wasps. The blue kills the ants faster and leaves a residue they will not cross. So good for doorways and around the baseboards. The red kills slower, have to have contact with ants. The residue does not last as long and the ants cross doorways in a few days. The only advantage of the red, it smells less than the blue. Hardly reason for me to not buy the blue next time.