You cannot get rid of Harlequin bugs, but encouarging its predators to hang around can help. Be sure you have properly identified them before trying to control them and that there is a real good reason to control them. What are they doing that requires your control efforts?

Here is a link that might be useful: Harlequin bug

Thanks kimmsr. It is certainly the harlequin bug that I have in the garden, though it isn't identical to the one pictured in the link you sent. I had it identified at the state museum here. It is a sucking insect, so ruins tomatoes, for example. Keeping the place tidy will help, apparently, as they spend the winter under rubbish but the compost bins provide protection for them too.

I certainly appreciate your help.

kohelet

What is a predator of the harlequin? They ate my broccoli and my cleome this year.

booliebumskie I wish I knew too....they decimated my brassicas last year. This year I am using trap crops, and 'hiding' the kale from them.....My russian kale is still intact but I see some telling white marks on the leaves of some of the lacinato... Nothing like last year though. By the way, I use collards as traps when I want to grow kale (the Harlequins seem to like the collards better) and I have also been using radishes as trap crops surrounding my brussels sprouts and cauliflowers. So far so good.

How to get rid of them? I used to come home from work, put on the latex gloves, and hand exterminate them. I would catch them and toss them in a small bucket that had some soap, water, tobacco juice and hot pepper juice. That works, but it is not the most fun I have ever had.

I have heard that chickens will not even go near them. Birds are supposed to be predators for them, but guess what, the Harlequins (Murgantia histrionica) know how to extract toxins from the crucifer plants so they make themselves distasteful to the birds, this way they do not get eaten! I am giving the link for that article. Amazing.

If anyone has other good tips for control, please post. There is a good article on using trap crops (I will post later when I find it), but it is focused on the green stink bugs (Nezara viridula) rather than the harlequins.

Here is a link that might be useful: Harlequin bugs making themselves taste bad

What is a predator of the harlequin?

Maybe birds?

As a rule pests are more numerous than predators. It has to be this way or the predators would starve to death. It's the whole prey (plant eaters) vs predators (flesh eaters) thing.

There are many ideas to control/limit the damage of pests, but when the population is high forget about all of it. Control them using the least toxic methods that wipe them out or don't. That's the choice.

Predator bugs are great for preventing [some] pests from increasing in numbers to the point controls are required to get a harvest, but once pest populations explode to the point crop damage will or is occuring the use of predator bugs is past.

Most people looking for predators of the Stink Bug family look for those that would predate the adult, forgetting the the best time to control them is the egg stage, and recent research at the University of California has found the the ubiquitious Pill Bug will eat those eggs, or the nymph stage and there may be several of the normal predatory insects that work on them but we don't really know because no one has really looked. The adult Stink Bugs emit a very disagreeable odor and that is alos very distasteful.
Floating Row Covers can be helpful.

I've never heard of this organic insecticide, but it's recommended for control of harlequin and stink bugs:
Sabadilla is an insecticide produced by grinding the seeds of the sabadilla plant, Schoenocaulon officinale. For several years sabadilla products were not available in the U.S. However, they are now sold by several mail-order suppliers, and garden centers have begun to carry sabadilla products as well.

Sabadilla is both a contact and stomach poison and has shown greatest promise against several of the "true bugs," such as squash bug, chinch bug, harlequin bug and stink bugs. It has proven effectiveness against leaf-feeding caterpillars, Mexican bean beetles and thrips. Use of sabadilla on certain vegetables, including squash, cucumbers, melons, beans, turnips, mustard, collards, cabbage, peanuts and potatoes, is permitted by the EPA..

The ground seeds of sabadilla sold for garden use are considered among the least toxic of the various botanicals. However, sabadilla dusts can be highly irritating to the respiratory tract, often provoking a violent sneezing reaction if inhaled. Be sure to wear a dust mask when applying it and, as with all pesticides, follow precautions listed on the product labels. In addition, several of the alkaloids in sabadilla can cause rapid depression of blood pressure in mammals.

Has anyone heard of anything further, positive or negative, about it?

Sabadilla is an alkaloid just as nicotene and ryana are. Because it is highly toxic to many insects and bees this should be only considered for last resort use. Pyrethrins are a better choice but are also now used as last resort controls.

I find they're easy to knock off the plants, at which time I step on them, hoping this will encourage diseases that will control the population. I've also tossed diatomaceous earth on them, but can't tell if it helped or not - seemed to decrease the population somewhat. My plants had 2 or 3 bugs per leaf at one point.

productor de Semillas de cebadilla.Tengo 25.000 kilogramos

Bug Beater and Yard and Garden Insect Fog might be an organic solution. I found it on the Bonide site. They also had an organic insecticide oil that mentioned harlequin bugs, too, but I lost the reference. Look under insecticide. Attached is the picture of my harlequin bugs and the poor kale they decided to make their home.

OK, here's the link for Japanese Beetle Killer.

http://www.bonide.com/products/product.php?category_id=196

This claims on the label to be a natural killer and lists Harlequin Bugs as one of it's targets.

The agent that kills is: pyrethrum

Oh, it's not sold in some states, like mine (California). Perhaps it's not really good for the environment. See what you think.

Pyrethrin, and the synthetic form pyrethroids, are very braod spectrum poisons that can be used with a greeat deal of care.
Like most other poisons the will kill off beneficial insects as well as the pests. Hopefully where they are spraying the pyrethroids to kill off the msquitoes that might cause West Nile Virus they are taking precautions that will limit the death of beneficial insects.

I understand Spinosad can help to control this nasty pest. If not gotten under control quickly, I've been advised to pull all infested plants. They will quickly expand from brassicas (kale, cabbage, cauliflower, etc) to other plants (such as spinach, chard, even giant sunflowers) so it's important to act immediately upon spotting them. Good luck.