Answer: These shield shaped black and orange pests are a type of stink bug, releasing a foul odor when disturbed. Their distinctive eggs, which resemble neat rows of tiny white barrels with black hoops, are laid in precise double rows on the underside of leaves. Both the adults and the nymphs suck the plant sap. They make their appearance known by bleached or yellowish patches on plant leaves. They can kill a plant by their voracious feeding. Generally there are 3-4 generations in a summer.
The best way to control harlequin bugs is in the fall during garden clean-up. Destroy the debris in your garden where the adults have overwintered and discard it in the garbage...not the compost! You can also:
1) Buy resistant crop varieties, such as Vale Kale and Headstart or Early Jersey Wakefield cabbage.
2) Use row covers before the first bugs appear.
3) Use a soap spray which can be effective.
4) Handpick them when they first appear in the spring.
5) Try a "trap crop." Bait them with cabbage and kale leaves (which they love) elsewhere in the garden destroying the decoyed bugs every day. Turnips and mustard are two of their favorite crops and are sometime planted as "trap" crops to lure them away from the other crops they are damaging.
6) Feed the soil! Remember that plants grown in healthy soil are able to resist disease and pest attacks better. Adding organic matter to the soil is the easiest soil booster there is!
If all of these techniques fail, and you do resort to a pesticide, try pyrethrum which is an effective pesticide against harlquin bugs. When using pesticides, always be sure to follow label directions carefully--including making sure the product is labelled for both the plant and the pest.
Sabadilla is a botanical insecticide is made by grinding the seeds of the sabadilla lily (Schoenocaulon officinale) into a fine powder. Though it is effective against a range of true bugs (Hemiptera) as both a contact and stomach poison, it is also highly toxic to bees, and is highly irritating to mucous membranes of mammals. It's becoming more and more difficult to find this product as newer, more targeted materials and techniques become available.
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