Invasion of the stink bugs
Asian insects found in area, could pose threat to orchards
Friday, June 20, 2014 8:19 AM
Yet another invasive insect has apparently found its way to southeastern Minnesota - one that could become a headache for both farmers and homeowners.
The brown marmorated stink bug (BMSB) is a native of China, Korea, Japan, and Taiwan. Accidentally introduced to the United States in the mid-nineties, the species has now been found alarmingly near La Crescent area apple orchards.
That's a problem, since the bugs puncture fruit and suck out juices while feeding. They end up injecting saliva into those wounds, which leaves a dimpled surface on the apple, with rotting and corking underneath. Fruits can also become deformed. Needless to say, the result is unsalable apples.
The BMSB invasion is already causing "severe agricultural and nuisance problems" from Pennsylvania through Virginia according to the University of Minnesota Extension. The pests actually feed on over 300 different species of plants, including tomatoes, soybeans, green beans, cherries, raspberries, pears, and sweet corn. Besides the dimpling of fruit, leaf stippling, and destruction of seeds, the possible transmission of plant pathogens is a concern.
Homeowners won't be fond of BMSB either. They overwinter in houses, garages, and barns to survive winters, similar to box elder bugs and Asian lady beetles. One documented case found an estimated 26,000 in a single home.
The insects resemble other stinkbug species, with a distinctive shield-shape. They can be distinguished from other types of stinkbugs by light and dark bands that fringe the abdomen, striped antenna, and rounded shoulders.
Now found in 41 states, BMSB has been detected in Minnesota in the Twin Cities metro area and Duluth, with infestations in nine Minnesota counties so far. When they turned up in nearby Winona, it raised a red flag for LeCrescent apple growers.
True to their name, the bugs emit an odor that some have compared to dirty socks, and others describe as an earthy smell that resembles cilantro. The BMSB emits the smell by secreting a defensive liquid from the underside of the thorax when threatened.
The good news is that BMSB is not expected to become a severe threat in Minnesota for several years, according to experts. That might allow state agencies, farmers and others to take some defensive measures of their own.
The Minnesota Department of Agriculture is attempting to pinpoint just how far the bugs have spread within the state, and U of M Extension entomologists (with help from the U.S. Forest Service) are currently investigating biological controls to use against the pest. One example of that is a Chinese parasitic wasp that is known to feed on the insect.