Fig. 1. Kudzu bugs on soybeans. Photo from bugwood.org, by J. Greene, Clemson Univ.
For the pest four or five years, farmers and homeowners in Pennsylvania and the rest of the Mid-Atlantic region have gotten to know the brown marmorated stink bug.
This pest species was accidentally introduced around Allentown in the 1990s, and has since spread out of our area to much of the country.
As bad luck would have it, the region is about to get to know another invasive stink bug species. The new beast is known as bean platasipid (Megacopta cribraria), but is commonly referred to as kudzu bug for its tendency to feed upon kudzu, an exotic invasive weed common in the southern U.S.
When kudzu bug feeds upon kudzu, it can be considered a beneficial species, but in the southeastern US kudzu bug has become a serious pest of soybeans. This stink bug species is much smaller than brown marmorated stink bug and an obviously different shape (Fig. 1), but like brown marmorated stink bug it also can overwinter in homes and other buildings.
This stink bug species was discovered in Georgia in 2009 and has since spread through out the southeast and is heading north. Most recently it has been discovered in Sussex County, Delaware and four counties in Maryland (Anne Arundel, Calvert, Charles, and Prince George’s counties).
We fear it will be discovered in Pennsylvania soon and are asking folks to keep an watchful eye and let us know if you find something that looks like it. We need to document its presence and let Pennsylvania Department of Agriculture confirm its identity.
Moving In On Tennessee, Kentucky
Doug Johnson, University of Kentucky Extension entomologist, has been talking about the arrival of Kudzu bug in Kentucky for the past two years
Fortunately, he says, the invasive pest has not arrived in the commonwealth but it's approaching the area. His colleague in Tennessee, Scott Stewart, is dealing with Kudzu bug infestations in several southeastern Tennessee counties.
Like Kentucky, most of Tennessee’s soybean production is in the western portion of the state. None the less, this activity in eastern Tennessee provides a foothold in our area and represents the infestation closest to Kentucky. In addition, this probably represents establishment (a locally overwintered population) and not introduction because this pest was discovered in eastern Tennessee in previous years, he says.
"It is as yet unknown how important this pest will be in Kentucky soybeans. However, it has become a major pest within two years of discovery in the soybean production states to the south of us. I see no reason to believe that this will not be the case in Kentucky. It is therefore important for us to keep a watch out for this pest," he says. "My guess is that it will first appear in counties with kudzu along the interstate corridors that handle traffic from east Tennessee, the Carolinas, Georgia and Alabama. This includes I-75, I-65 and I-24. Producers and other interested parties would do well to look for this bug in kudzu and soybeans that border these highways."
Though kudzu bug is new to the United States, not known to be present in Kentucky, and has no other species in the same family in the Americas, it should be pretty easy to identify, Johnson says.
The adult Kudzu bugs are 1/6”- 1/4” long, oblong, perhaps the size of an English pea; are olive-green colored with brown speckles, and produce a mildly offensive odor when disturbed. In the United States, characteristics of the adult kudzu bug useful in distinguishing it from other stinkbugs include: the plate in the center of its back (called the scutellum) is broader along the rear than it is along the head end, and much wider than it is long. The kudzu bug has a round body shape rather than the triangular to semi-elliptical body shape of our native stinkbugs as well as a distinctive head shape.
Kudzu bug eggs are small and barrel shaped similar to stinkbug eggs, but are laid in a double row laying on their side rather than sitting upright in a cluster.
Nymphs are the immature forms that hatch from the eggs. Their overall body shape is similar to the adult, but smaller, and they appear to be “fuzzy” or “spiny” while the adults are smooth.
Kudzu bug Facts
Though the kudzu plant aids in overwintering and is a reproductive host, our colleagues in the “deep south” have shown that the kudzu plant is NOT required for kudzu bugs to establish. Soybean will do just fine.
Kudzu bugs are infesting several soybean fields in southeastern Tennessee.
Kudzu bugs are now established in Alabama and Mississippi.
Kudzu bugs are now in Virginia, but not on a direct interstate route to Kentucky.
Kudzu bugs are most detrimental to early planted soybeans.
Current research in the Carolinas and Georgia indicate that treatment is required when there is an average of 1 immature or two adults per sweep.
One of the biggest mistakes in kudzu bug control is spraying too early, requiring a second unnecessary spray.
Kentucky soybeans along the I-75, I-65 and I-24 corridors are likely at the greatest risk. These interstates bear traffic directly from infested areas.
Kudzu bugs are also home invaders. They will try to get into structures during the winter months.
The place to find all things kudzu bug is: www.kudzubug.org