Do they ever stop?
The Lowdown: Why are the beautiful ones the most evil? These tiny Picasso paintings will lay waste to all cruciferous vegetables. If these types of veggies are scarce, the Harlequin will turn to valuable edibles like asparagus, corn, beans, squash, and tomatoes. Young plants will die with a heavy infestation, and older plants will become stunted and less productive. According to NC State’s Ag extension, female adults will lay approximately 155 eggs, and there are usually two to four generations in a season.
Biological Control: A boundary of trap crops like radishes and collards will help. Some harlequin bug-resistant crops include the Savoy Perfection Drumhead (cabbage) and the Snowball X & Y (both cauliflowers). Also, clearing out plant debris at the end of the year will get rid of overwintering adults. However, this will also get rid of any beneficial bugs overwintering. Finally, consider adding plants that attract parasitic wasps. This non-stinging species of wasp will lay eggs in the host harlequin, leading to an eventual gruesome death. Attractant plants include caraway, cowpea, sweet fennel, and yarrow.
Insecticidal Control: The sprays available for control are minimal at best. A spray combined with potassium salts of fatty acids will help to dehydrate the bug before knocking it out with a pyrethrin.
The Lowdown: One day, you’re looking at the most gorgeous tomato plant ever created by human hands and soil. The next day: a skeletonized version of your beloved heirloom beauty. The culprit is the dastardly tomato hornworm, its appetite is responsible for taking down a healthy plant in a smattering of days. Their camouflage color makes them hard to see before the destruction is obvious. They also enjoy dill, eggplants, peppers, and potatoes. They have two generations here in the South and one in the North.
Biological Control: Plant marigolds near tomatoes. Not only is it a lovely border, the hornworms hate its pungent scent. Use dill and borage as trap crops. However, the gorgeous swallowtail butterfly caterpillar also loves dill, so exercise caution when spraying.
Here’s a picture of the swallowtail caterpillar and ensuing butterfly:
The parasitic wasp also enjoys using the hornworm as a host. Look at the above list on Harlequin bugs for plants that attract the wasp.
Here’s a lovely pic on what the wasp does to the impregnated hornworm:
Human Control: Handpicking is a popular method, followed by an execution with garden scissors or a drop in a bucket of soapy water.
Insecticidal Control: Quite a few pest sprays work without having to resort to no-discretion sprays like pyrethrins. Sprays and powders that have BT (Bacillus Thuringiensis) will kill the hornworm. These products include Dipel Dust, Dipel DF, and Safer Caterpillar Killer. Spinosad (found in Monterey Garden Spray) is another effective bacteria that will attack the hornworm’s nervous system.
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