Black onion aphids attack all alliums, so if you have chives, leeks or onions growing in your garden, then keep an eye on and treat these as well. These pesky black critters have the habit of hiding down in the overlapping leaf bases, out of the reach of predators. As soon as you see them, spray with a dilute soap solution making sure it drips down to the leave bases. Follow up the next week with a pest oil. If there is still some sign of the aphids then repeat this.
