As things started to get warm this summer (i.e. late June), we got some major aphid infestations. I didn’t catch it right away and it was pretty bad on my cabbage.
I used an organic spray called EcoSMART which contains Rosemary Oil, Peppermint Oil, Thyme Oil, and Clove Oil. It doesn’t smell very bad. They say you should avoid contact with you skin. I got some on my hands and didn’t find it irritating at all. The oil in the product actually drowns soft-bodied insects like Aphids and Caterpillars.
After spraying, wait a day or two for the pesticide does to do its thing. Then spray with water to get all of the aphids off of the plant.
Once you have an infestation you need to be vigilant. Watch all of the neighboring plants as they’ll move around. They’re not that bad to deal with if the infestation is small. Once you see them, get out there every day if you can. Check regularly as the weather starts getting hot. You can quickly go from no infestation to a large infestation.