Catalpa aphid Catalpa aphid: two millimeter-sized aphids. Dark yellow to yellow-green colored. Catalpa aphids: photo: Beatriz Moisset - CC BY-SA 4.0 Catalpa aphid (Aphis catalpae). Two millimeter-sized aphids. Dark yellow to yellow-green colored. Where to find Catalpa Control Control with pyrethrum, Insecticidal soap, soap suds, rhubarb spray or nettle spray. Prevention Natural enemies of the catalpa aphid include: birds, ladybird, earwigs, parasitoid wasps and lacewings. Provide a variety of plantings where these enemies of the Catalpa aphid feel at home. Related items Aphid Cabbage aphid Currant blister aphid Green peach aphid Honeydew