Q: Could you advise me where I can purchase horticultural oil? Or is this something I can make myself?

A: Horticultural oil is a specially refined oil that suffocates insects without hurting your plants. I discourage you from making it yourself. Cooking oils and automotive oil will not control insects. Most nurseries carry some sort of oil product for insect control. This is a great time to use horticultural oil to control scale insects.