Neem Oil - Neem oil is approved in California for use on ornamental and food plants. It is derived from the neem tree. Aphids, caterpillars, loopers, mealy bugs, thrips, whiteflies, and diseases like mildew and rust are effectively controlled.
It is most effective when alternated with another insecticidal soap or pyrethrum, giving a one-two punch, killing insects in different stages of development. Follow label instructions. Spray 2 or 3 times every 7 to 10 days. As with all horticultural oils, do not spray if daytime temperatures will exceed 90F. -www.mastergardeners.org