The delicate white or purple flowers of Dark Opal basil (Ocimum basilicum "Dark Opal",) common basil (O. basillicum,) Spicy Globe basil (O. basilicum "Spicy Globe") and Greek bush basil (O. minimum) repel flies, mosquitoes, moths and aphids. Basil planted near tomatoes repels hornworms.
Marigolds (Tagetes spp.) repel whiteflies. The marigold"s roots give off a noxious odor that permeates the soil. Marigolds are sun-loving annuals that are easy to grow. Their bright orange, red and yellow flowers are used as borders or edging plants in the garden. ??Nasturtium (Tropaeolum minus) and celery repel white cabbage flies.
Plant curley parsley (Petroselinum crispum) and flat-leaf Italian parsley (P. crispum neapolflanum) together with carrot seeds to repel carrot flies. When used as a companion plant to carrots, Prostratus rosemary (Rosmatinus officinalis "Prostratus") and sage (Salvia officinalis) also deter carrot flies.
Horehound (Marrubium vulgare) is aromatic and pungent. The plant"s bitter taste and strong fragrance repels flies and mosquitoes. ??Tansy (Tanacetum vulgar) presents bright-yellow, buttonlike flowers that emit a fragrance effective in repelling flies. Early American settlers planted tansy by doorways and hung clumps in windows to repel unwanted flying insects including flies and mosquitoes. ??Lemon thyme (Thymus x citriodorus,) common thyme (T. vulgaris) and French Narrow Leaf thyme (T. vulgaris "French Narrow Leaf") repel whiteflies in the home garden. ??Lavender (Lavandula angustifolia) repels flies and attracts butterflies, honeybees and hummingbirds.