Monday, April 8, 2013

Kudzu Bug Update

A clearer picture of the impact of the kudzu bug on Georgia's roadsides, farms, and gardens is slowly emerging as information from across the state is gathered and evaluated by personnel at UGA.

The map below shows the speed at which this particular pest is spreading across the Southeast:


At a meeting about four weeks ago, Wayne Gardner, an Entomologist at UGA,  shared some very useful new information about these little stink bugs. It turns out that - so far -  they are most damaging to kudzu and soybeans. They don't seem to damage peanuts, but they have been observed feeding on wisteria.They also are seen on many other legume-family plants, but the amount of damage they inflict on those is unclear.

Gardner listed host plants for the kudzu bugs, and those that are legumes include: Lima beans, pole/string/green beans, lablab beans, pigeon peas, wisteria (both American and Chinese), American Yellowwood, lespedeza, peanut, crimson clover, clover, alfalfa, sicklepod, and black locust.

Non-legume host plants include: alligator weed, black willow, banana, cocklebur, cotton, fig, loquat, muscadine grape, pecan, pine trees, potato, satsuma mandarin, tnagerine, wax myrtle, wheat, and wild blackberry.

On most of the host plants, the bugs are present as adults, but they aren't reproducing on the plants, and the amount of damage done is yet to be established. The kudzu bugs are present in all stages of the lifecycle on soybeans and kudzu, and they damage soybeans and kudzu primarily by feeding on the stems rather than the leaves. 

Gardner reported that kudzu biomass in infested stands is reduced by about one third within a year's time, which is probably good news for our roadsides. For soybean farmers, the average 18% reduction in crop yield is markedly less-than-good news. For urban areas, it may turn out that the worst problems relate to the stink and the staining caused by the little pests, and some people may have a localized allergic reaction to contact with the bugs. Hopefully, the picture will become even more clear this season, as more data are gathered and added to what we already know.

11 comments:

  1. They love mandevilla.

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  2. Good to know. Thanks! So far, they really love the parking lot at the Extension Office, too, and my white car especially. I haven't seen many in my yard, but I'm probably bringing them home, a few at a time, every day. I hope some local bug/bird decides to think they are a delicacy soon!

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  3. I have an infestation of swarming adult kudzu bugs on the south side of my house. I'm trying to figure out whether it's possible that the two 14inch pots of tomato plants that I bought from Costco could have something to do with it... or is it more likely that they came from bark mulch in my neighbor's yard?

    I have no Kudzu, no soybeans and no wisteria in my subdivision. Will the bugs harm my tomato plants? Will they move on in search of kudzu or beans to eat and Is there a likely time period for them to vacate my property? As it is, I can't go out on my deck because it's the most sunny and warm spot and they're swarming.

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  4. Kecohen,

    You are not alone in being faced with astonishingly massive swarms of kudzu bugs. They are not currently in my yard, but they seem to be everywhere else. This week's issue of Southern IPM News has a brief article about the bugs here:

    http://ipmsouthnews.com/2013/05/20/north-carolina-kudzu-bug-treatment-thresholds-evolving/#more-1230 .

    The pertitent bit of information is this:

    "Adults are flying from over-wintering sites and searching for their reproductive hosts, wisteria, kudzu and soybeans.

    "In the meantime, they can be found nearly everywhere. I have seen photos of these insects on nearly every plant you can imagine, as well as the sides of houses and pickup trucks. Insects likely aren’t feeding or reproducing on these things (certainly not feeding on houses), so property owners will have to remain patient, while growers who planted soybeans on the early side might be getting a bit jumpy with the influx of adults into their field."

    The bugs do succumb to most of the standard chemical bug sprays (for exasperated homeowners, the Extension specialists are recommending things that contain carbaryl, malathion, or pyrethroids like bifenthrin), and I am hopeful that the insect-eating birds are after them, too, but for most people the solution to the problem is going to be waiting for the bugs to move along.

    Hopefully, you won't have too long to wait! -Amy

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  5. Hi Amy,
    Thanks for your reply. Here's the scary part: They are alighting on my deck and laying eggs! I have no plants there. It's just a very sunny spot for them. I've spayed down the adults and the eggs, but I've no idea if the poison will kill the eggs or whether I have to wait until they hatch.

    It was my understanding that their odor makes them repulsive to birds and they have only one natural predator, a tiny asian wasp that manages to kill the eggs.

    I'm also confused as to where they have come from... at present I seem to be the only one with an infestation of the stinky things. I think they're coming from my neighbor's yard. Perhaps some bark mulch or the stand of cyprus trees that border his yard and back up to my row of townhouses.

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  6. kecohen,

    Could you email me a picture or two of the bugs and eggs? My work email is amy.whitney@cobbcounty.org .

    So far, yours is the first report I've seen/heard of eggs being laid on something that isn't a leguminous plant. I can forward your photos to the guys at UGA who are working on the problem.

    Thank you! -Amy

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  7. Hi Amy,

    I just finished sending you a few photos I took on my phone. They aren't the best, but I'm sure that the one of the Kudzu bug will be good enough for identification. At the moment there are only a few flying around and alighting. By around 3pm the place will be thick with them again and I won't be able to go out there. I'll need to wait until dusk. They seem to love the sunshine and quite down when the sun is either behind the clouds or on the other side of the house.

    Karen

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  8. The pictures arrived, and I've sent them to a couple of specialists at UGA. Will let you know when I hear back. Thank you!

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  9. Looking forward to their response. Thanks!

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  10. We have a reply! Your tomato is safe, and the adults likely did not come in on either the nursery plants or the mulch. As noted in the Southern Region IPM article, the bugs are emerging (en masse) from their over-wintering spots, which include cracks in tree bark.

    They will be a nuisance until they go find some kudzu, which should be soon since the weather is finally warming to good-growing-temps for the kudzu.

    The adults that are laying eggs on your deck are old, in bug-terms, and they will be dying soon, now that they've been laying eggs. If the eggs hatch, the larvae won't survive long because there is nothing on your deck for them to eat.

    The UGA research group has been testing the Asian parasitoid wasp (in quarantine conditions) on the bugs, and so far, the kudzu bug seems to be the only host for the wasp, which improves the odds of the wasps' being approved for release sometime in the foreseeable future, but not in time to help your yard.

    At least, though, there is some assurance that the infestation will not go on much longer!

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  11. OK, well that is good news. They didn't say if there was a way to kill the eggs. It seems that my big mistake was crushing a few of these guys. I read where they are attracted to their own odor and tend to aggregate. I can certainly testify to that, according what I've seen. Anyway, I'm hoping not to ever see them again. If I do, I swear I won't touch them with anything but a hot soapy water spray. :-)

    Oh, one more thing... I think the fact that they were laying eggs on the black grill cover is significant since all the literature so far was saying that they are only attracted to light colored objects. NOT!

    Thanks again so much for your help, Amy.
    Karen

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