What smelly pest from the east is described as a voracious eater and has attracted the attention of National Public Radio, the Washington Post, Wall Street Journal and many more nationally-recognized media sources? What is all the stink about some nasty and elusive insect that seems to be able to appear out of nowhere? Name that same bug that the USDA has listed it as its top ‘invasive insect of interest.’
While most of us have long been aware of stink bugs, it is the Brown Marmorated Stink Bug (BMSB) that is generating an extraordinary level of interest from USDA and Extension researchers, farmers, gardeners and the press. The quest to control this pest has grown so quickly that a new website, www.stopbmsb.org has been created to share information about the six-legged critter and how best to manage it.
At a recent Ohio State University Extension Soybean Workshop, Entomologist Dr. Andy Michel cited the BMSB as a serious threat to the United States’ 3 billion bushel soybean crop, the majority of which is produced in corn belt states. The repugnant insect was unintentionally brought over from Asia and has few natural predators in this country. Originally discovered along the East coast munching on fruit, vegetable and ornamental crops, the pest made it to Ohio in recent years and has since stretched across a number of other states.
Michel pointed out that crushing it releases a more foul odor that one smells when stomping on a Multicolored Asian Lady Beetle, a natural predator to soybean aphids. Of course, homeowners never appreciated the overwintering affinity of the indoors possessed by this species of lady beetle. Beware, easterners have found that the BMSB is also a fan of indoor habitation during cold months.
True to the name, all stink bugs are offensive to the human nose. As mentioned previously, most of us in the Midwest grew up disliking stink bugs, but we mostly knew of the green and brown species which in most years were just minor pests of field crops.
Last year, the red shouldered stink bug (has a red band on its shoulder) was discovered in high numbers in some soybean fields.
The Brown Marmorated Stink Bug appears to be a more dangerous pest based on experiences of states to our east. The aggressive insect will most likely be noticed after the R2 growth stage, when the soybean plant is in full bloom. The greatest damage occurs when they pierce through the pod, then feed on the seed. Stink bug feeding can go on throughout the pod fill, requiring scouting vigilance throughout most of the soybean’s reproductive period.
As with many insect pests, monitoring the edges of the field is the highest priority. Although sweeping with a net is probably the best way to track most stink bugs, combining growth stages and species. The economic threshold for treatment is four bugs per sweep set of 10 sweeps. The BSMB is hard to sweep and is best done visually; 1 - 2 per foot is the treatment threshold.
Other insect species will require scouting from soybean emergence on through pod fill. Bean leaf beetles can cause some stand loss on earliest planted fields, then show up again later in the season. Soybean aphid predictions are up in the air right now, since none were seen overwintering on buckthorn anywhere in the Midwest. Japanese beetles can contribute to a leaf feeding frenzy if conditions are right.