Question: My kale was beautiful 3 days ago, but is suddenly infested with bugs that are black, white and orange. They have 3 white dots just behind the head. The body has an orange stripe down each side and has horizontal black and white stripes. What are they and how can I get rid of them?
Answer: Based on your photo and description, these are the nymph stage of the harlequin bug, Murgantia histronica (Hahn). They are common in Atlantic, Cape May, and Ocean counties, though they can also be found in other counties in New Jersey.
Adult bugs are ⅜-inch long and mottled red, black, and yellow or orange. Eggs are cylindrical (barrel shaped), yellow to light gray with black bands, about 1⁄30 inch long, and resemble small kegs with black hoops. Young nymphs are green with black marks, and older nymphs are like the black and orange adult coloration, however they are slightly smaller and lack wings. Though their coloring is similar to the adult, the color pattern is different. The harlequin bug is a true bug (has a triangular shaped thorax) and has a shield shaped body. Coloring may change slightly with the season. These are a type of stink bug and all stages will emit a smelly odor when crushed.
Adults and nymphs of the harlequin bug pierce stalks, leaves and veins with needle-like mouth parts and extract plant juices from cabbage, cauliflower, collards, mustard, Brussels sprouts, turnip, kale, kohlrabi, radish and horseradish. They are partial to the cabbage family, but if there is a heavy infestation, harlequin bugs may also feed on asparagus, bean, beet, corn, eggplant, lettuce, okra, potato, squash and tomato. Plants damaged by these bugs develop irregular cloudy spots around the puncture wound. Young plants may wilt, turn brown, and eventually die while older plants become stunted or deformed.
Harlequin bugs overwinter in sheltered areas in or near the garden. They can hide in winter crops and in organic debris. In the spring, they emerge, and the females lay their eggs on the undersides of leaves. In this area, they usually have two generations per year.
There are several things you can do to reduce harlequin bug infestations. The first is choosing vegetable varieties that have a resistance to or a tolerance to these bugs. Hand picking of bugs is an effective method of eliminating this pest, although the bug’s odors may be repulsive to some gardeners. Be sure to wear disposable gloves. If your garden is not already infested, you can use floating row covers to exclude this pest from your garden. Cleome (spider flowers) can be grown as a trap crop in a border around your garden. These plants will attract the harlequin bug, which gives you the opportunity to dispose of many of them before they move on to your cole crops. Future harlequin bug infestations can be disrupted by cleaning up debris and plowing under crop residue in the garden as winter approaches to limit sites for adults to overwinter. Seek out and destroy eggs, nymphs and adults.
(Reference: Rutgers Fact Sheet 246, Harlequin Bug.)
For more information on harlequin bugs, you can contact your local extension office. Atlantic County residents can contact the Master Gardener Helpline at 609-625-0056. Cape May County Residents can call 609-465-5115, ext.3607.
Atlantic County Master Gardeners will be available to answer gardening questions and take samples for plant identification or diagnoses throughout the county this summer. You can find at the Hammonton Green Day Festival, Sept. 21. We will also be available at Atlantic County Library branches throughout the county evenings in the fall. Please check with your local library for a schedule.
Interested in our Junior Master Gardener Program? We will have an information session 6 p.m. Sept. 16 at the Rutgers Cooperative Extension Office in Mays Landing. Call 609-625-0056 and ask for Brittany Rigg or Kendrin Dyitt for more information.
Do you have a gardening related question you would like answered here? Please forward your questions to Belinda Chester, Master Gardener Program Coordinator, Rutgers Cooperative Extension Office, 6260 Old Harding Highway, Mays Landing, NJ 08330. You can also submit questions at Rutgers-atlantic.org/garden or email them to email@example.com; please include “garden question” in the subject line.