If you catch them early enough, lace bugs will go away with garlic spray. More entrenched infestations may need to be treated with pyrethroid insecticides. Neem oil is also effective, IF the temperature isn't above 29º C within 24 hours of application. I'll admit that I have never seen lace bugs on olives, but I also don't know what species of lace bugs are found in Oz. :)