Kudzu bugs may face natural predator

dworthington@heraldonline.comMay 17, 2013 

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Natural biological warfare may stem the increasing wave of kudzu bugs throughout the South.

Researchers from Clemson and North Carolina State universities, the University of Georgia and other institutions are expected to ask the U.S. Department of Agriculture for permission this week to fight the kudzu bugs with its natural predator – a small wasp the size of a gnat.

The kudzu bug and the wasp – Megacropta cribaria and Paratelenomus saccharalis respectively using their scientific names – are native to Japan, China and India.

Studies in Japan give the researchers hope they can help keep the kudzu bug population in check, but not kill it totally.

A solution to her bug problem can’t come soon enough for Beverly Semone of Hickory Grove in western York County. While there isn’t kudzu growing near Semone’s home, the kudzu bugs have made her fig tree their temporary home.

Kudzu bugs eat and lay their eggs in kudzu plants. They also eat legumes such as soybeans.

Semone said she examined her fig tree Wednesday morning and there were some kudzu bugs near the top of the tree. When she looked later there were no bugs. She hoped they had gone. Instead, they, and more kudzu bugs, had congregated at the bottom of the tree.

“They are an aggregating insect,” said Paul Thompson, York County’s Clemson Extension Service horticulture agent. “They are attracted to each other’s company.”

Thompson said the recent cool weather may have slowed their activity. Instead of feeding on kudzu, the kudzu bugs “are just hanging out,” he said.

Thompson said he had a couple of complaints about kudzu bugs and fig trees this year. While there is some evidence the bugs have “investigatively probed” the fig stems there hasn’t been any damage, he said.

Semone tried using her shop vacuum filled with soapy water to rid her fig tree of the bugs. That’s one of the ways researchers have recommended to remove live bugs.

In an email Semone wrote that, “This is not a easy as it seems, but I do think it will work. . .

“It worked best by holding the vac under the branch where it was stronger and below where they collect on ends and the stems. I gave it a good shake and many of them dropped down and got sucked up by the vac. They stick and you have to get the brush and flick them.

“I took a small 1-inch paint brush and flicked off the ones that flew around and landed on the leaves.

“I had on a white t-shirt. No! No! No!. They were all over me and I had to suck them off of me.” The bugs are attracted to white and light colors.

Thompson said, “Most of the complaints I get are from people who say they can’t go outside and enjoy themselves because of the bugs.”

Semone wrote that when the bugs land on you, “they give you the creepy crawler feeling.”

The kudzu bugs release a chemical that can stain skin and in some cases cause a blister, said Jeremy Greene, a Clemson University entomologist with the Edisto Research and Education Center in Blackville.

All of the kudzu bugs in the South trace their lineage to one mother bug. Researchers say the mother bug either entered the U.S. from Japan via Hartsfield-Jackson Atlanta International Airport in 2009, or plant material with her eggs did.

With no natural predator, the kudzu bug population has expanded dramatically. There are kudzu bugs in every county in Georgia, South Carolina and North Carolina, researchers said. The bug also has been found in Alabama, Florida, Tennessee and Virginia.

It takes approximately six weeks for a kudzu bug to go from an egg to adult. Spring is the time they hatch and seek food.

In agricultural settings, the kudzu bug attacks the stems of soybeans, sucking out the water, affecting the plant’s size and its yield. In some cases, Greene said, soybean yields can be reduced by as much as 60 percent.

Timely spraying of pesticides can kill the bugs, Greene said. Clemson researchers are trying to determine when the optimal time is for pesticide spraying.

Residentially, there are fewer options if you have kudzu bugs, researchers said. The bugs feed on the kudzu plants and lay their eggs there in the spring.

“If you live next to a kudzu batch you will have to deal with it all year,” Greene said.

People should seal as many cracks or crevices as possible on their residences, researchers said. Screening, especially on soffit vents and other roof vents, can prevent kudzu bug entry into homes, they said.

Dominic Reisig, a researcher at North Carolina State University, said pesticide sprays will usually kill the kudzu bugs, but the spray doesn’t last long enough to keep the bugs from returning. There is also the health hazard of spraying pesticides overhead into soffits and roof eaves.

Kudzu bugs found indoors should be vacuumed, not sprayed, researchers said.

A large number of dead bugs should be removed immediately. They can attract secondary pests such as carpet beetles and ants, Greene said.

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