What you see plaguing your plants are, no doubt, harlequin bugs, and yes, they are harmful to your plants in the brassica family – broccoli, greens, cabbage turnips and kale. This time of year, the bugs you see are probably the adults. They use piercing mouth parts to extract the juices from all parts of the plants, and heavy infestations can cause severe damage – you may see discolored spots on the plants. The leaves of young plants may wilt and die, and mature plants will become stunted.
Getting rid of them can be a challenge. Toxic Free NC, A website devoted to non-toxic solutions to pest problems, suggests removing them by hand if there are only a few (drop them into a bucket of soapy water), or if there are large numbers and you are willing to sacrifice the plants they have damaged, trap them in large garbage bags, seal the bags and let them bake in the sun for a few days.
It’s always good to encourage the natural predators of damaging insects to visit the garden. Praying mantises eat harlequin bugs and other stinkbugs, so if you see them around, don’t shoo them off. There are parasitic flies and wasps that are among stinkbugs’ natural predators, and birds, spiders and toads also enjoy them as a food source.
As a last resort, Toxic Free NC suggests insecticides that are approved for organic farms, such as rotenone, pyrethrin, Neem oil and insecticidal soap. Note that these products can be harmful, so be sure to follow label directions and use as little as possible. These insecticides can also kill the bugs you want to keep, so spray only in the morning or late evening when those insects may be less active. Insecticides are most effective on the pests in the younger larval or nymph stages. The adult bugs are resistant to sprays.
To prevent the bugs from finding your plants in the first place, Toxic Free NC suggests using lightweight floating row covers over your brassica crops, making sure the edges are weighted so the bugs can’t get to the plants. It also helps to control weeds in the garden, as stinkbugs are attracted by weedy areas in or near the garden, they advise.
Filed under: Fall gardening, Insects, Plant pests | Tagged: brassica family, broccoli, bugs, cabbage, Greens, harlequin bugs, insecticides, kale, natural predators, organic gardening, Stinkbugs, turnips |