Winning the War on Harlequin Bugs

Recently, I came home from a two-week long trip and eagerly headed out to the vegetable garden to see how things had fared under my husband’s care. Predictably, he’d done a great job keeping up a watering schedule through an unusual heatwave, with temperatures regularly reaching the mid and high nineties for several weeks. For the most part, everything looked great, despite a bit of slowed growth on peppers and tomatoes because of the heat. I found leaning garlic stems ready for pulling, artichokes ripe for cooking, onions thriving despite the heat, butternut squash dangling from vines, zucchinis and flying saucer squash hiding in the leaves—I could hardly contain my excitement over what I deem our most successful garden to date. “The only things not doing well are the radishes,” my husband said, almost as an afterthought. “They’re crawling with bugs.”

I went to investigate and found my husband wasn’t kidding. The radish bed was infested, and I do mean infested, with Harlequin bugs, a shield shaped black and orange bug that’s part of the stink bug family. The bugs live with quite a reputation for their destructiveness—I had been warned of them during the last summer season from a friend’s post on Facebook, but thankfully, they’d never made it to my garden. Harlequin bugs are attracted to cabbage, kale, mustard, broccoli, and other members of the brassica family, and when pressed for food, will eat tomatoes, squash, beans, corn, and other vegetable plants.

My joy immediately turned to fear for my thriving and beautiful garden—the heat wave showed no signs of diminishing (Harlequin bugs thrive in heat) and they were mating all over the radish plants. I immediately turned to Google to look for a sustainable solution, but for the most part, organic gardeners were pessimistic when it came to Harlequin bugs. They don’t have many predators—chickens, birds, and other bugs won’t eat them because they put off an offensive smell, and the bugs reproduce at an alarming rate—five times a year! I searched and searched, but the most effective solutions required chemical products that would kill beneficial bugs as well—products we don’t use at En Saison Paradise! So, we went to work testing the various organic techniques suggested and it turns out that a combination of methods is the way to win the war on Harlequin bugs.

Method One – Trap crop

If you’ve got Harlequin bugs, chances are you already have a trap crop—ours turned out to be the radishes. The downside of this method is that you must give up the crop—you pull the infested plants and discard them into the trash. We were able to harvest our healthiest radishes, but all of the plants, ready-or-not, were plucked from the garden.

Method Two – Hand pick the bugs

As soon as we discarded the infected plants, the remaining bugs flew to our beloved squash plants. I zeroed in and began squishing them with a gloved hand, but they put out an odor and soon, any time I came near the frightened bugs, they quickly hid, smelling the remnants of bug death on my glove. The little guys seemed to get the message though and fled my squash plants, and overall things were looking better for the garden. Or so I thought.

While watering, I discovered that a nearby Butterfly Bush was also infested—there they were again, making love all over the stems and leaves! Back to the internet. Now I tried the method of hand catching the bugs and throwing them into in a pail of soapy water. I killed about 40 bugs this way  but most of the bugs escaped my hands and flew away. The ones thrown in the soapy water died within minutes though—apparently the soap damages their shells and they fall apart. Still, it was difficult to catch them, and I kept thinking there had to be a better way.

Meanwhile, my husband sat at the computer researching organic home-made insecticide . . .

Method Three – The War is Won!

After researching numerous home-made organic insecticide recipes we settled on a recipe we found on That called for 2 quarts of water, one large onion, two bulbs of garlic, 2 tablespoons of cayenne pepper, and 2 tablespoon dish soap. We blended the ingredients listed in a food processor (except for the soap) and then transferred the mixture to a bowl where we added two quarts of water. We let it soak for an hour or two before transferring into two one-quart spray bottles and then added a tablespoon of Dr. Bronner’s Pure Castile Hemp-Peppermint liquid soap to each bottle.

The finish off required a few days of diligence and was a bit like hunting. We spot checked and searched for remaining bugs each morning and evening, and every time we saw the bugs, we hit them directly with the mixture (being careful not to spray bees). The combination of the soap, garlic, onion, and cayenne pepper was too much for the little critters to bear. Now I’m hard pressed to find one of the little buggers for a photograph.

I’m a softy who really takes no pleasure in killing bugs, but I must say, I’m breathing a huge sigh of relief at ridding my garden of Harlequin bugs. You can get them out of your garden too – and sleep well knowing that no birds, bees, beneficial bugs, or earthworms will be harmed in the process.

Buh-bye Harlequin bugs!