|Organic Solutions for Harlequin Bugs and other Stink Bugs
A Factsheet from Toxic Free NC
About | Identification | Life Cycle | Prevention | Getting Rid of Stink Bugs | Sources
About Harlequin Bugs and Stink Bugs
The Harlequin bug is a type of stink bug that causes trouble for many gardeners in the Southeast (see picture A). Other stink bug pests in North Carolina include the Green stink bug (see picture D), Brown stink bug, and Southern green stink bug.
All are pests of many crops, but they especially love plants of the brassica family. The brassicas include cabbage, collards, broccoli, mustard, turnips, and kale. During heavy outbreaks, or when all their favorites are gone, Harlequin bugs will eat other garden plants such as squash, okra, tomatoes, corn, beans, and tree fruits.
Both adults and nymphs cause damage. They eat all parts of the plants, including stems, leaves, fruits, and seeds. They use piercing mouth parts to suck out plant juices. Damage on leaves and stems looks like uneven discolored spots around a hole (see picture C). Young plants may wilt, turn brown, and die (see picture F). Mature plants may survive but growth is slowed. Damage on fruits such as squash, tomatoes and okra appears as dark holes surrounded by bumps, pits, or white-yellowish spots. The lighter spots do not ripen to the same color as the rest of the fruit. Fruits may also dimple or grow in strange shapes.
The tips below are designed to help you control stink bug damage in your garden. Sustainable pest management strategies usually work best when used together. Think about your garden, your resources, and your time, and put several of these tips together into a plan that works for you. [top]
Identifying Harlequin Bugs and Stink Bugs
Adult stink bugs are about half an inch long and shield-shaped (see picture D). Their colors range from dark brown, tan, to green. The Harlequin bug is black with orange, yellow and red markings (see picture A).
Nymphs are similar to adults but smaller and with a more rounded shape (see pictures C and E). Eggs are barrel-shaped. They are laid in groups on stems and the undersides of leaves, and may be yellow, green, pink, gray, or striped (see picture B).
It is important to note that not all stink bugs are pests. Some predatory stink bugs, such as the spined soldier bug, actually attack other garden pests. They should be encouraged in the garden. The spined soldier bug looks similar to the brown stink bug, but has spikes standing out on its shoulders (see picture G). [top]
Stink bug adults spend the winter in old plants and other garden litter. They come out in the early spring to begin laying eggs. In early spring eggs take up to 20 days to hatch, but as the weather warms they may hatch in as few as 5 days. Nymphs mature into adults in 5 – 8 weeks. Populations tend to grow through the season, getting heaviest during early to mid fall. There are two to four generations per year in North Carolina, depending on the species. [top]
1) Grow healthy organic plants. Strong plants can handle some damage from stink bugs better than weak, struggling plants. Make sure that your crops are getting enough sunlight and water. Ensure that the soil is well-drained, and rich in nutrients and organic matter. [top]
2) Grow resistant varieties. Some types of brassica plants are naturally resistant to Harlequin bugs. NC Cooperative Extension recommends the following varieties:
Cabbage: Copenhagen Market 86, Headstart, Savoy Perfect Drumhead, Stein’s Flat Dutch, Early Jersey Wakefield.
Collards: Green Glaze.
Cauliflower: Early Snowball X, Snowball Y.
Radishes: Red Devil, White Icicle, Globemaster, Cherry Belle, Champion, Red Prince. [top]
3) Till in late fall. Tilling crop leftovers into the soil once cold weather has arrived can reduce the number of adult stink bugs who survive the winter. Then fewer come back out the following spring. [top]
4) Control weeds in the garden area. Stink bugs are attracted by weedy areas in or near the garden. Weeds should not be allowed to spread in the garden. Weedy areas around the garden should be mowed before spring planting and regularly after that to keep stink bugs from hanging around.
5) Use row covers. Keep stink bugs from finding your crop by covering your brassica plants with a lightweight “floating” row cover such as Reemay. These materials (as opposed to plastic or heavier fabrics) let water and air through and do not block very much sunlight. They can be found at garden supply stores or ordered from seed catalogs. The covers can lie directly on the plants (the plants will lift the cover as they grow), or you can support the covers with wire hoops. The trick is to keep the edges of the covers tightly buried or weighted so that the stink bugs cannot get in. [top]
Getting Rid of Harlequin Bugs and Stink Bugs Without Toxic Chemicals
6) Scout and hand pick. Hand picking stink bug adults, nymphs and eggs early in the season can really help you control them later in the year. Likewise, hand picking in the fall can cut down the number of adult stink bugs that come back the following season. Scout the garden often throughout the year. When you find stink bug adults, nymphs, or egg clusters, crush them with your fingers. Or, since stink bugs really do stink when you squish them, it might be less smelly to drop them into a pail of soapy water. [top]
7) Plant a trap crop. A trap crop is one planted to lure the stink bug away from your main crop. For instance, if you have had a problem with Harlequin bugs on your spring cabbage, next year plant mustard on the edge of the garden early in the season to lure the adults as they come out. Later, kill the “trap” mustard crop along with the pests by sealing them all together into plastic garbage bags and leaving them in the sun to bake for a few days. Then, plant your cabbage in another part of the garden. But beware – stink bugs can move fast, so make sure that you don’t just scare them out of the trap crop and into another part of the garden! [top]
8) Attract natural enemies. Stink bugs have many natural predators who can be invited to hang around the garden. Wildflowers and herbs will attract parasitic flies and wasps. Predators such as birds, toads, spiders, and praying mantises will make their homes in perennial herb and flower beds and small shrubs near the garden. [top]
9) Release predators. Minute pirate bugs eat stink bug eggs and nymphs, and praying mantises can attack adults. These can be bought and released into the garden. Look for them in garden supply catalogs. [top]
10) Organically acceptable insecticides. As a last resort, you might choose to apply least-toxic insecticides that appear on the Organic Materials Review Institute’s list of products approved for Certified Organic farms, such as rotenone, pyrethrin, Neem oil, or insecticidal soap.
Even though these sprays are approved for organic farms, they can be hazardous, so be sure to follow instructions on the labels very carefully. Keep in mind, too, that these insecticides can kill pollinators and other “good bugs” you want to keep in your garden. Use as little as possible, and spray only in the early morning or late evening when the “good bugs” are less active. Insecticidal soap can burn the leaves of your plants, so do not spray them in direct sunlight or when temperatures are above 80 degrees.
Insecticides are usually only effective in slowing squash bugs down, not stopping them. Adult stink bugs and their eggs are very resistant to sprays. Spraying should be done soon after the first eggs hatch and the nymphs have come out. The sprays must come into contact with the nymphs to work, so try to cover the whole plant. Weekly sprays may be needed since new stink bugs hatch all season long. Obviously, even “organic” sprays come with risks and problems, so try the other tips here first, and you may be able to skip the sprays altogether. [top]
||This factsheet was written with the needs of non-commercial home, school and community gardeners in mind. Certified Organic growers, or those seeking a certification, should check with their certifying agency before using ANY insecticide. Some organically acceptable insecticides are approved for use in Certified Organic systems only against certain pests or in certain situations.
Ellis, Barbara and Bradley, Fern Marshall, editors. The Organic Gardener's Handbook of Natural Insect and Disease Control: A Complete Problem-Solving Guide to Keeping Your Garden and Yard Healthy Without Chemicals. Rodale Press, 1996.
Flint, Mary Louise. Pests of the Garden and Small Farm: A Grower's Guide to Using Less Pesticide, 2nd Edition. University of California Press, 1998.
“Harlequin Bugs.” Insect and Related Pests of Vegetables. Center for Integrated Pest Management, North Carolina State University, NC Cooperative Extension Service. Viewed March, 2012: [link]
Bambara, Stephen and Casey, Christine. “No Romance in Harlequin Bug Infestation.” North Carolina Pest News, North Carolina State University College of Agriculture & Life Sciences, Departments of Entomology and Plant Pathology, NC Cooperative Extension Service. Volume 19, Number 17, August 6, 2004. Viewed March, 2012: [link]
“Stink Bugs.” Center for Integrated Pest Management, North Carolina State University, NC Cooperative Extension Service. Viewed March, 2012: [link]
Ipsan, Annette. 2010. “How to Manage Stink Bugs.” University of Maryland Extension – Washington County. Viewed March, 2012: [link]