Wednesday, October 21, 2020

Brown Marmorated Stink Bug

The brown marmorated stink bug Halyomorpha halys is an invasive species of stink bug native to East Asia. Their home range includes China, Japan, Korea and other Asian Countries. It was first discovered in an established population in Allentown, PA in 2001, although reports of it's presence began as early as 1996. It is believed it made its way into our country via shipping containers of cargo from one or more Asian countries where it is endemic. 

They are similar in appearance to other stink bugs native to our country, however the striped antennae is a distinct identifying characteristic. The term "marmorated" is descriptive of the veined or marbled markings unique to this species. They measure approximately 3/4 of an inch in length with nearly the same width. Body is shield-shaped, like nearly all stink bugs. Their color is generally dark brown with a lighter colored underside, but there may be shades of gray, light brown, copper, red, or purple with a slight iridescence depending upon how the light reflects off their body.

Current governmental regulations do not require that intervention be taken when dealing with stink bugs. Had this not been the case it is possible these bugs would not have taken such a stronghold within the Eastern United States. Had they been deemed a potential threat to crops within our country they could have been stopped or at the very least slowed down when first discovered. Since their first discovery in 2001 they have now been found in nearly all 50 states and are considered a serious pest in ten states and a nuisance in more than 20 states. Missouri is classified as a nuisance state, but Tennessee, a not too far away neighbor, is a considered a serious pest state for this insect. So how long before they become a serious threat here? Who knows. The key to their success is their ability to travel. They can tolerate extreme cold and heat fairly well, and they are known for hiding out in human structures, which includes cargo containers and vehicles. What better mobile transport than a car, RV or cargo container to get you from one place to another? Once moved to a new location their ability to adapt and thrive allows them to easily establish a new population. 

They are responsible for millions of dollars in damage to numerous crops, including nuts and fruits, agricultural crops like soybeans and corn as well as ornamental plants destined to be used for landscaping. Their piercing mouth part, called a proboscis is used to stab the plant and suck the juices out much like a straw. This damages the fruit meant for human consumption and must be thrown out. In corn crops they are a little sneakier. They access the cob though the husk and feed on the corn, hidden from site. Their presence is often not known until harvest time, when yield is drastically reduced and damage is discovered. In soybeans it is much the same, they enter the pod and feed on the bean seed. Damage is often not noticed, unless you are very observant. Look for beans that "stay-green," even after other nearby fields have turned brown and died back. This green appearance is indicative of the feeding damage done by this stink bug. Typically they feed within the first 40 or 50 feet of the fields edge, creating what is know as an edge-effect. If infestation is severe pesticide usage may be required. Experimentation is being done to find a biological control for these pests. The Samurai Wasp from Asia is known to parasitize these bugs, and in their native range may control anywhere from 50-80% of the population. So far in the United States we are not seeing this type of averages, it is closer to 10-20%. Other predators such as spiders and wheel bugs are known to feed on them. Pill bugs (rolly-pollies) eat the eggs.  Wheel bugs are showing a lot of promise as a bio-control predator as they feed on the eggs and the adults readily. However it will take a LOT of wheel bugs, pill bugs and wasps to tip the scale back into balance.

As a nuisance, they are much less devastating, but still annoying. They are prone to entering homes in fall when the night time temperatures drop below 45 degrees. They will begin aggregating on buildings, including our homes. Sometimes their numbers may be in the hundreds or even thousands. It is reported that in one home, over the course of 161 days over 26,000 of these bugs were removed. That's a lot of stink bugs to live with! They are not reported to bite, but if mishandled I am certain that piercing mouthpart could puncture skin. Their frass (feces) may stain surfaces and they stink! Although their smell is said to smell like cilantro, so if you like that smell it could be you won't find that part of their arsenal offensive. To help prevent them from entering your home in the first place, seal all cracks and crevices with silicone caulk, fix screens on windows and doors, use draft dodgers along the base of doors, use a vacuum to pick up any wayward individuals that make their way in. Be careful when considering the use of pesticides in your home. Remember they are chemicals and can cause their own set of problems, especially if not used correctly. If your infestation is terrible or more than you can deal with consider contacting a trusted pesticide company to help.