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mexican bean beetle control options

username_5
16 years ago

So, every year my beans get chomped on by the mexican bean beetle. I think the name is actually mexican bean LEAF beetle, but since they take little bites out of the beans leaving unsightly black spots...

So, who is troubled by them and what ways have you tried to control them that didn't work well?

What ways have worked well?

I was thinking of giving Safer BioNeem a try this year.

Comments (37)

  • tedp2
    16 years ago

    Spraying with malathion or sevin will knock them on their kesters and keep them away until rain washes it off. I understand there is an organic poison called BT that gets them too but takes longer time.

  • gardenlad
    16 years ago

    Bt is a natural insecticide (actually a bacteria) usually used to control soft-bodied pests, such as cabbage worms. There are different bacteria involved, and you have to get the right one for the specific pest.

    For bean beetles I do two things. One is hand picking them. And the other is interplanting petunias with the beans, which helps deter them.

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  • username_5
    Original Author
    16 years ago

    tedp2,

    I don't know if you are aware or not, but Sevin kills 75-100% of the earthworms in areas it is used.

    Unfortunately while this fact is well researched and documented it isn't something the company puts on it's label.

    If you value the role worms play in creating and maintaining productive soils this is one product that should never be used.

    Don't mean to lecture and I hope nobody takes it as such, it is just that I have found so many experienced gardeners who do not realize that Sevin is an extremely potent worm killer (again, because the makers don't see fit to tell us this).

  • paquebot
    16 years ago

    Sevin and the like are forbidden in our community garden and bean beetles were rampant for awhile this spring. I'd never previously worried about them since they were always cyclical in that they'd often really chew up the first few leaves and then be gone for the rest of the year. However, couldn't get away with that this year with probably 30 gardeners growing beans and every one in a near-panic mode from seeing so many holes. In the end, I did advise dusting with rotenone 1% and the problem vanished. After a week, no fresh holes anywhere in the complex.

    Martin

  • rodger
    16 years ago

    I plant petunias and marigolds but still get eating alive by the Mexican bean beetle. they start with the green beans then the butterbeans and finally the peas. Last year I attended an Heirloom Garden lecture by Dr. Bradshaw from Clemson University. He runs a couple acre Heirloom vegetable garden at the SC Botantical gardens and his beans are never destroyed by beetles. This garden is 100% organic.and his secret is a parasitic wasp from India that only eats MBB larvae. I also does not over winter in North America so you have to buy each year. I ordered some and this is the first year I am not eaten up with the MBB. The wasp (Pediobius foveolatus) is the size of a sugar ant. The adults lay their eggs on the MBB larvae and the developing maggots devour it from the inside out. Then they emerge in 10 days to start another generation. They are 100% effective and only eat the MBB. Adult wasp feed on necture. The University of Maryland is the only place that raises them but they don't retail only wholesale through other companies. I bought mine through Bio control in Tenn. I have attached a link below. I will have some info on them and will bring some live wasp if still around to the 3rd annual AHSC in Berea KY. this Oct. ( Good excuse to come)

    Here is a link that might be useful: Pediobius foveolatus

  • gardenlad
    16 years ago

    Great tip, Roger. And I hope you can bring some. Either way, be prepared to discuss them (I will make time for you), because beans are such an important part of every members' collection.

    BTW, for those interested, the AHSC (Appalachian Heirloom Seed Conservancy) Fall Conference will be October 6-8. Nonmembers are invited to attend.

    For details, contact AHSC at KentuckySeeds@hotmail.com

  • aka_peggy
    16 years ago

    Whew, that Pediobius foveolatus is expensive!

    The 1st year I gardened here, the MBB attacked my limas. I handpicked. Then I didn't see a one for the next 3 yrs. Then last year my beans suffered another attack. I always hand pick and that does work to keep them under control but it can get tedious.

    Gardenlad, any idea where I might find the BT that's specific to MBB? A google search turned up nothing.

  • gardenlad
    16 years ago

    Sorry if I wasn't clear, Peggy. Far as I know, Bt is _only_ for soft-bodied pests like caterpillers. I don't know of any version that controls MBB.

  • aka_peggy
    16 years ago

    Oops...Gardenlad Yes, I did misunderstand. I have BT (Bacillus thuringiensis )and I will try it on the MBB this year if they show up.

  • rhizo_1 (North AL) zone 7
    16 years ago

    Here's the deal with the Bt. There are several different strains of Bacillus thuringiensis. If you have the kind that is labeled for caterpillars, it will not work on ANYthing but caterpillars! If you have the kind that is labeled for mosquito or fly control, it will not work on anything but those critters! However, there are a couple of Bt strains that are labeled for MBB!

    Bt var. San Diego OR Bt var. tenebrionis

    These would be specialty products, but have seen them in some of the catalogs.

  • aka_peggy
    16 years ago

    Thanks Rhizo, I was able to google that up. Now where do I find this stuff?

    Here is a link that might be useful: Bt var. San Diego OR Bt var. tenebrionis

  • rhizo_1 (North AL) zone 7
    16 years ago

    Hey, Brendan. That article is about the Bt strain that affects caterpillars, which is Bacillus thuringiensis var. kurstaki (Bt-k).

    Again, it has nothing to do with the other bacillus strains.

    Peggy, I'll bet that some of the on line places that sell biological controls sell the MBB bacillus.

  • organic_nut
    16 years ago

    great information.

  • brendan_of_bonsai
    16 years ago

    Actually, its not about BT-K at all, it is unfortunately mostly about BT corn, which is transgenic corn with BT protiens from various strains, However, anyone who knows about BT should feel more than encouraged to edit the article.

  • rodger
    16 years ago

    AKA Peggy, yes the wasp is expensive but when you grow as many beans as I do (I have over a 1000 feet in beans/Peas) It is very cheap and to be 100% effective. I checked out Bio-controls website and they do have the BT San Diego, listed for Potato beetle control. You could e-mail them to see how effective it is on MBB. But again with the wasp no spraying every week just release and forget it mother nature takes control.

  • brendan_of_bonsai
    16 years ago

    Why is it that parasitic wasps that are uber selective are always from a different area than what they are selective for, these Indian wasps seem to eat only Mexican beetels larve, There is a Canadian Wasp that seems to eat only amber marked birch leaf miners which are from europe, how did these wasps end up wanting to eat only one thing, and have it be a thing that lives so very far away from were they are found?

  • rodger
    16 years ago

    Good question, I will have to find that out. My quess would be that the wasp feeds on something else in its homeland and through trail and error reseachers have found that they will also eat for example the MBB and no other native insects, but a very good point.

  • jimster
    16 years ago

    Rodger's guess about the wasps and beetles makes sense to me. It's analagous to tomatoes, which we grow far from their place of origin and get pollinated (well, really just get an assist) by bumblebees, which don't exist in their native environment.

    My only garden insecticide is rotenone dust. It works well on bean beetles. It is completely nontoxic to humans and other mammals, although it will kill bees and fish. However, my gardens have no drainage into waterways and I do not use rotenone on plants in flower. I use a light application and only when necessary. I don't mind holes in leaves, I just don't want the plants decimated. I don't know if it is toxic to earthworms. I'll check on that because it would concern me.

    Seems like the predatory wasps would be a good solution for community gardens, where the cost could be divided among many gardeners. It might be difficult to get a concensus on doing that, but it might work.

    Jim

  • username_5
    Original Author
    16 years ago

    -- My only garden insecticide is rotenone dust. It works well on bean beetles. It is completely nontoxic to humans and other mammals, although it will kill bees and fish. --

    You may want to take another look. The information I have suggests Rotenone is moderately toxic to humans and mammals. Studies have shown that rotenone reproduces symptoms of Parkinson's disease. It is also highly toxic to earthworms from what I have read, but rarely actually kills them due to breaking down in the soil quickly.

    Here are a couple links for further reading:

    http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC35133#Toxicity
    http://www.jneurosci.org/cgi/content/short/23/34/10756

  • brendan_of_bonsai
    16 years ago

    I don't think that the bee is a good parallel really, we use European honey bees to polinate, they are generalized polinators, there are south american honey bees too that are generalized polinators, I'm just confused about specific critters like parasitic wasps that eat only one type of bug round these parts, and beetles taht are used to controll one type of plant.

  • jimster
    16 years ago

    Thanks for setting me straight, username and Brendan. I was off the mark in both cases.

    Jim

  • glover
    16 years ago

    Great information. I'm part of a community garden, and that wasp sounds like something we might want to invest in. I grow green beans in my small plot every year with great success - however, beetles are almost always rampant by the 4th of July. This year, they've not really started yet! I've always handpicked and think it does reduce the damage and keep the plants going.

  • rhizo_1 (North AL) zone 7
    16 years ago

    username, I am so glad that you brought the information about rotenone to the forefront. This chemical has raised some yellow flags for me for quite some time.

    Has anyone experimented with and observed anything of interest regarding Neem for the control of beetles? I sure have heard and read about great results but have not had the opportunity to try it myself.

    Parasitism is a fascinating subject. The evolutionary mechanism is remarkable! There are many organisms so locked into the life cycle of another, that they would become extinct if the other creature were to die out. That's something of a flaw, don't you think? ;-) Others evolve to be less species specific, thereby increasing the chances of success. The insect world is full of parasites and parasitoids. Finding ways to use these relationships has been a source of interest to us measly humans for thousands of years. Hopefully, we don't see too many examples that end up with results we didn't intend! No one predict with certainty how any given organism is going to act and react when introduced into another environment.

    Here's an article some of you might find interesting.

    Here is a link that might be useful: FYI

  • aka_peggy
    16 years ago

    The bean beetles have moved in and set up permanent quarters in my bush green beans. I don't see any on the pole lima beans yet. They've already done significant damage to some plants. I have Neem oil and would like to use it but I'm afraid the temps are to warm to use an oil spray. But I'm afraid if I don't do something soon they'll be wiped out. I have rotenone but I hesitate to use that too.

    What if I shooed all the bees away, sprinkled rotenone and covered the beans with remay for a couple of days? Any thoughts?

  • aka_peggy
    16 years ago

    The weather report says the temps will drop overnight to the upper 70's so I'm going to use neem oil this evening and hope for the best. I'll continue handpicking as well.

  • username_5
    Original Author
    16 years ago

    Please let us know how the neem works for you, Peggy. I got a late start this year with beans (actually the rabbits set me back ;-) so I will be giving it a try not too long from now if they show up again. Can't imagine they won't.

  • aka_peggy
    16 years ago

    Most beans have been sprayed and so noted on the calender. It was a bit time consuming though. As I turned the leaves over to spray I HAD to smoosh any beetles and eggs that I saw...it gives me such pleasure. One thing about Neem, it leaves a milky residue on the leaves so it's easy to tell if you missed any leaves. I'm sure I missed plenty so I'll continue smooshing/drowning them over the next few days.

    I still have other, smaller bush beans that need to be treated. I don't see any damage on those yet. I think I might put remay over them to buy time and I'll give all pole beans a blast tommorow AM. I will report back in a week to 10 days.

  • gardenlad
    16 years ago

    Just wanted everyone who was interested in Roger's comments on the predatory wasp to know that he will be giving a presentation on organic pest & disease control of legumes at the Appalachian Heirloom Seed Conservancy's annual Fall Conference, October 6-8, in Berea, Kentucky.

    Non-members are welcome to attend.

    For information about the conference, or for membership data, contact AHSC at KentuckySeeds@hotmail.com

    By the by, in addition to the line-up of great speakers, and the ever-popular Saturday night cook-out, the conference includes two formal seed swaps. Last year something like 80 common bean varieties were sold and/or traded, plus butterbeans, limas, runners, and cowpeas of all sorts.

    The seed swaps, alone, might make attendence worthwhile.

  • usafarmer
    16 years ago

    Has anyone noticed sulfur dust to have any deterrence against mexican bean beetles?

    Has anyone used chickens or guinea fowl to pick the bean beetles off the beans?

  • aka_peggy
    16 years ago

    Oops! Time flies doesn't it? Sorry I didn't report back as I said I would.

    I sprayed my beans with Neem on the 4th...the weather people predicted the temp for the following day to be 77°. Well...it was actually 84° and within a few days after treatment, it looked as if someone had poured oil on my beans. I didn't think they'd survive but they have. It did seem to help reduce the population of bean beetles however. The bean plants that were sprayed look terrible as if they have rust. None of the other beans (in other parts of the garden) have this "rust" or whatever it is. I finally broke down and dusted with Rotenone once. Otherwise I continue to handpick. Production doesn't seem to have been affected but some of the beans have small holes like I've never seen with MBB.

  • gullywash
    16 years ago

    I have a severe problem with the bean beetle, not the mexican bean beetle. Do you think Pediobius foveolatus would be effective on this beetle also? I was thinking of planting again, even though it is quite late because green beans are one of my most favorite vegetables. I'm in zone 4b, do you think I have a chance? Are beans daylength sensitive?

  • lilacs_of_may
    15 years ago

    I sprayed Neem oil on my melons and squash to try to control flea beetles. Did nothing that I could see. I continued to lose plants. So I finally dusted with rotenone. Two of the squash are still alive. So I dusted some of my brassica with rotenone, because they were being eaten by something else, not flea beetles, the holes are too large. Looks like a caterpillar of some kind, although I haven't seen what's eating them.

  • happyday
    15 years ago

    Lilacs, have you seen any white cabbage or yellow sulfur butterflies fluttering around?

    I sprayed with Sevin a month ago to control flea beetles on the radishes/turnips/beets. Still have enough earthworms to keep the moles coming to the buffet. The only beetles I still see are the fireflies resting on the bean leaves during daylight hours.

  • farmerjeanne
    12 years ago

    Was reading all your posts on Mexican bean beetles because for the first time ever this year I'm really battling them. They started on the green beans and are now on the winter beans. I was away for a week on vacation and that's when they decided to descend, apparently, in very healthy state. Always before, I could squash as I found them and always won the game. I'm worried I might not this year. So, we've started a great squashing campaign, and we will take no prisoners! I sure don't want to use pyrethrins--for one thing, my neighbor keeps bees---there are so many good guys out there that I just don't want to go that route. My husband, who's a biologist by training,thinks that the Bt which I use on my broccoli--successfully-against the cabbage worms will work on the bean beetles...the larval stage, of course. Even though they don't become moths or butterflies, they are truly caterpillars at that stage. So, just finished spraying all the beans to the best of my ability. Whew. We shall see. I'll post updates so you all can know the results.

  • pnbrown
    10 years ago

    Any updates on control with bt?

    I got hit hard this year, am considering buying the wasp next year. One wonders, how does the UofMD overwinter the wasps?

  • jimster
    10 years ago

    "One wonders, how does the UofMD overwinter the wasps?"

    I believe they, and other suppliers, propagate the wasps in greenhouses.

    Jim

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