Kudzu Bugs - The Invasion Begins
If you read my recent post about the kudzu vine, then you know that it is an invasive species here in the US but native to Asia. In the 1950s, it became popular as a cover crop to help prevent soil erosion along road cuts, and it thrives in those areas even today. So well, in fact, that most casual passers-through get the impression that the stuff has taken over the south. Today, we’re going to talk about another Asian invader that arrived on its coat tails: the kudzu bug.
Kudzu Bug (Megacopta cribraria)
Kudzu bugs are small, olive green insects with black speckles on their back. They first arrived in the US in 2009 when they showed up at Hartsfield-Jackson Atlanta International Airport, but they are quickly spreading throughout the Southeast. They were first reported here in Arkansas as early as 2014, but there still hasn’t been an official report of them in my county of Craighead. I submitted a report, so I may be the first!
... Awesome?!?
What Is A Kudzu Bug?
The kudzu bug gets its name from the fact that its life revolves around the kudzu vine, although they will also settle for other leguminous plants such as wisteria and soybeans. They depend on these plants for food, shelter, and as a nursery; however, as the weather cools, adults will move out of the kudzu to find their overwintering spots underneath debris, behind loose tree bark, or perhaps even in houses or other structures. They have a particular affinity for bright colors, so it isn’t uncommon to find them huddled together underneath the vinyl siding of your home to wait out the winter. When winter is over and spring rolls back around, these adults will leave their cozy nooks and crannies and fly back out into the kudzu to lay their eggs in rows on the leaves. This first generation takes about 6-8 weeks to mature, as they go through several instars. They will spend their lives in those tangled vines before spawning the summer’s second generation. It is this group of bugs that many people fear will move out of the kudzu and into the soybean fields.
Kudzu Bug Instars
Identification
Being the only representative of the Plataspidae family in the United States, identifying them is fairly easy. They have been described by some as looking like a brown lady bug, but I do not see the resemblance. Kudzu bugs are an olive green to brown color with black speckles. They can grow up to 6 mm in length, but the are generally wider than are long, and the caudal end of the back will be kind of bluntly squared instead of being round or coming to a point.
It is also possible to identify the sex of the bug by observing outwardly visible characteristics. If you take a look at the ventral view (underneath) of the kudzu bug, you will notice that it is made up of several plates called sternites. In males, the first two sternites will be a lighter color than the rest, whereas all or most of the sternites on a female will be that light tan color. You can see the difference in the images posted below. The male is on the left, and the female is on the right.
Male
Female
Take The Good With The Bad
Kudzu bugs have piercing sucking mouthparts that they use to drink sap from the vascular tissue of plants; and, since they gather together in large groups, they can quickly drain kudzu of its vital life fluid. In fact, some places have seen a ⅓ reduction in kudzu over just a two year period. Finally, a weapon that we can use to get rid of some of this stuff! But, what if they develop an affinity for soybeans? It appears as if they may already have. In studies, 16 out of 19 unprotected plots showed an average loss in yield of 18%, and and losses of up to 47% have been recorded in Georgia. Kudzu bugs can damage crops in several ways. Of course, heavy losses of sap can lead to dwarfed plants and smaller bean pods with fewer beans; but another problem arises after the bugs relieve themselves of waste. Their sugar-rich excrement can build up on the leaves and cause mold buildup that shields them from sunlight, making photosynthesis difficult.
Once Bitten; Twice Shy
I have seen these bugs around all summer, but I didn’t know what they were, and finding out wasn’t a priority. I kind of stumbled upon its identity while researching for a previous post about kudzu vine, and the thing that caught my attention was a report about a nasty bite from one** that caused a dime-sized portion of the person’s skin to die. With my curiosity piqued, I began to look more into the matter. What I found was rather surprising.
Evil Kudzu Bug
Kudzu Bugs Don’t Bite; They SUCK!
As I mentioned earlier, kudzu bugs have piercing sucking mouthparts not designed for biting. Most of the information that I was able to find about them claim that they can not bite at all. Even if they did, they do not possess any type of venom that would do the kind of damage that was report. So, what caused the skin damage?
Smelly And Corrosive
Kudzu bugs are distant relatives of stink bugs, and one characteristic that they share is the ability to secrete smelly chemicals when they are bothered. Unlike stink bugs, the chemicals released by the kudzu bug can cause some pretty severe allergic reactions. I don’t think the reported bite was a bite at all, but rather a bad reaction to the bug’s stinky defense chemical.
In Conclusion
Every since the kudzu bug arrived in the US, it has been working it’s way across the country. It has officially spread as far west as Arkansas and Louisiana and north almost to Pennsylvania. However, I have found them present right here in Craighead County in Arkansas, and there are claims that they have been found as far north as Maryland, but these do not show up on the official map. While they do not pose much of a threat to humans, they may become a nuisance if they try to overwinter on or in your house, and it is feared that they may disrupt American agriculture by decimating soybean crops. * All photos taken by me using Canon Rebel T3; Lens Model: EF-S18-55mm f/3.5-5.6 IS II. Macro shots were taken using a cheap screw on macro adapter; post processing performed using Darktable unless otherwise labeled.
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