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Communications > News Line > Posts > Kudzu Bugs No Match for Old Man Winter’s Persistence

kudzu-bug.jpgIf Old Man Winter deserves credit this year for reducing kudzu bugs, it is not so much due to his bite as to his persistence.

For the past few years, Dr. Xing Ping Hu, an Alabama Extension entomologist and Auburn University professor of entomology, and a team of researchers have been monitoring overwintering kudzu bug populations.
Fewer Kudzu Bugs in the Spring
She has concluded that there will be fewer of these malodorous pests to see and smell this spring.  Hu attributes the cause of these reduced numbers to this winter’s endurance rather than to its severity.

Until early last month, Hu and her researchers noted little difference in the mortality rates in overwintering kudzu bugs compared with 2013. 

“We noted in 2013 that some of the bugs emerged out of the dormant status of hibernation too early, used their energy and died when the temperatures dropped again in early February,” Hu recalls. “But then warmer temperatures set in and the insects rebounded.”
Hu initially expected the bugs to exhibit similar levels of resilience this year.   More of the kudzu bugs remained in their dormant status, with the ones hibernating underneath thick bark, vines and trees afforded the best protection against the cold.
Marked Changed after Early February
But things began to change markedly after early February.  Old Man Winter proved especially dogged and the chilling temperatures persisted.
That was the big difference between February, 2013, and last month.  As freezing weather persisted, more of the hibernating bugs began dying.
“Our last survey on March 7 revealed that more than 90 percent of overwintering bugs had died, compared to 70 percent in 2013,” Hu says, adding that males have suffered higher mortality rates than females.
Hu and the others have noted another telltale sign: Fewer of the bugs are flying out and mating as  spring approaches. 
“We’re noticing that most of the survivors are still in dormancy — a significant change from 2012 and 2013, when significantly larger numbers were observed emerging from their long slumber and flying out to mate as mid-March approached.”
Persistently cold temperatures are the reason, Hu contends.
While there was a couple of freezing cold days in February, 2013, namely February 22 and 23, there were long stretches of warm days too.
This year’s winter has been unusually and, most important from the standpoint of kudzu bugs, persistently cold.  Equally significant, there were fewer days that reached into the 70s.
The end result will be fewer kudzu bugs this spring, Hu says. Even so, despite the havoc this prolonged winter has played on spring kudzu bug numbers, Hu says the populations may increase quickly in the summer and fall, thanks to the pest’s immense reproductive capacity.
Other Insights into Kudzu Bug Behavior
In the course of investigating these overwintering bugs, she and her team have uncovered a few other insights into the pest’s behavior.
For example, both male and female adults overwinter in dormant states of hibernation.
“Our field observations reveal that the bugs feed on all kinds of plants to store food reserves later in the fall and then begin searching for protective places to overwinter — typically under tree bark and in and under tree litter.
She and other investigators also have observed that overwintering populations may come out flying during the hibernation period when warmer days exceeding 70 degrees arrive.  But they pay a heavy price for giving in to this false sense of spring.
“The cost of this behavior is a reduction in energy reserves and survival because there is no food available, even though they will have to go back to hibernating when the temperatures drop again.”
Other Insects Not Affected
Hu and her researchers have uncovered no evidence that other pesky insects such as fire ants, termites and carpenter bees have been similarly affected by the prolonged cold.
“We’ve observed new fire ant mounds popping up in fields and yards and a few kicks to mounds arouse hundreds of ants,” Hu says.
Termites have also been observed thriving in fallen logs and under tree bark.

And what about those industrious and persistent carpenter bees?  Hu and her team have observed them emerging from their galleries to begin their unrelenting search for flower pollens.

Homeowners should expect their peak foraging period to begin later this month, she says.


Sheron Mitchell

3/12/2014 11:12 AM
Good article.  What control methods can be used to rid our ornamentals (camelia and hydrangea bushes) of the kudzu bugs or just get rid of them in the yard area in general?

Application of Seven dust around the holes that carpenter bees bore, works well.  Is there anything else I can use on carpenter bees?

Xing Ping Hu

3/13/2014 2:05 PM
Mrs. Mitchell: Thank you for the comments.
Here are the responses to your question.
For kudzu bug control:  The good news is they are not resistant to insecticides. Any insecticide, even those over the counter products will kill them. If you like environmentally friendly methods, try white-colored sticky board/card. Setting the traps near plants you want to protect. Kudzu bugs will more likely to land and be caught by the sticky card than land on your plants. Another method you can use is to take advantage of the bug's "play dead" behavior. Place a piece of plastic or cloth under the plants they eat, knock the plants with a stick or kick the plant with foot, let the bugs fall on the plastic or cloth. Wrap they up or vacuum them up to kill them. Or you can let the bugs fall in a water-filled container to drawn them.

Control carpenter bees: puff powder pesticide, like Seven, into the exiting holes in wood. Other products such as the ready-to-use pressurized products for clack roach or wasps also work well. Regardless the products, do the application after dusk or in dawn when the bees are sleeping inside wood, and with caution to avoid stung. It is better to seal the holes after application because carpenter bees prefer to use old holes as new home

Marie Heaton

3/24/2014 11:27 AM
We have seen kudzu bugs for the first time around our home (south Alabama) in the last two weeks.  We first learned about them when we saw them in Birmingham two years ago.  They have now migrated to our area.  They have settled in my potted plants on my patio.  The last few freezes I have left my plants outside, hoping to kill the bugs, but some have survived and are still around - more it seems as the warmer days have come.  When should we expect them each year and how can I prevent them from getting in my potted plants?  Thank you.

Jason Hill

5/1/2014 2:57 PM
What makes the Kudzu bugs so invasive? Are they a threat to all plant life? How about grass? I prefer to use natural methods versus pesticides whenever possible. Is there a specific pesticide that is environmentally friendly that has been shown to do well with the kudzu bugs?

Julian Golec

5/27/2014 2:12 PM

The kudzu bug will now be a consistent problem for all residents in Alabama, last summer it was detected in all 67 counties. The migratory times of this insect vary, and are dependent on the temperature. In spring, most likely, you will see the bugs March-April. Fall will differ a bit, and they may be seen again in September-October. To prevent them from getting into your potted plants you may want to keep them indoors in a sunny area until the migration of kudzu bugs has ceased, and you see them less around your home. If you keep them outdoors, the best way is to prevent them from getting on the plants through isolating plants in a screen, or some other means of excluding them from landing on your plants.

Hope that helps, please feel free to ask any other questions!

Julian Golec

Julian Golec

5/27/2014 2:26 PM

All very good questions.

What makes the kudzu bug so invasive? There are many aspects to the kudzu bug that make it so successful in its new geographic range. The most important factor is the fact that the kudzu vine is pervasive throughout the southeastern. In the insects native regions (most of Asia) it feeds predominately on this vine, alongside some other legume species (namely Soy bean which also extensively grown in Asia). So, when it arrived in the U.S. in 2009 in Georgia, the bug(s) had no problem locating a food source and was able to feed and subsequently reproduce.

 They are not a threat to all plant life, certainly they are not a threat on grass. They do tend to utilize many plant species early in spring and late in fall when kudzu and soy are not available to them, but will only feed on other plants for a short amount of time. They are a serious threat, however, on legume species of all kinds, especially backyard beans.

In terms of safe pesticides, yes there are a few. Where do you plan on applying insecticides? you should never apply them directly to your home, or around residential structure. If you applying because they wound up on the outside of your home when they started to migrate, the best solution for that is power-washing them off your house. If they're inside use a vacuum to get ride of them. There are bio-rational insecticides, those that are Bt based that do well to kill the bugs.

Here's a link to an ACES publication on residential control, hope it helps. Please don't hesitate to ask anymore questions!

Julian Golec