Destructive Pest Brown Marmorated Stink Bug Coming To California: Agricultural Regions

These bugs are like nothing you’ve ever experienced before. If you don’t believe it ask the good folks who live and farm in the Mid-Atlantic States. The Brown Marmorated Stink Bug, Halymorpha, halys, has been all over the news east of the Mississippi and has recently made headlines in the South and the Pacific Northwest. The Brown Marmorated Stink Bug first arrived in the United States around 1997 in shipments arriving from Asia in Allentown Pennsylvania. First Collected and identified there it has since multiplied by the square and made its presence made known in a big way.

With no significant natural enemies on the North American continent and being an excellent hitch-hiker it has now spread to both coasts and has been sighted in 33 states and the District of Columbia. In states where it is well established its numbers are in the millions and growing. In autumn it invades homes and businesses by the dozens to thousands as it seeks shelter from the cold winter weather. If disturbed or crushed it emits a foul substance that smells like a cross between cilantro and dirty socks. But BMSB is more than a nuisance. The list of host species for the insect is long. It feeds on cultivated plants as well as weeds. It’s feeding causes significant damage to field and orchard crops, making the products unmarketable as fresh produce. Losses to home gardeners, farmers and orchardists in the Mid-Atlantic have been from 25 to 100 percent with revenue losses in the millions.

In 2010 the species established itself in Northwestern Oregon and Southwest Washington and is multiplying quickly. It was also sighted in Southern California last year. Considering the speed at which this bug is spreading it will likely reach the Sacramento, Central and Salinas valleys within a few short years. In the eastern US the winters are long and cold, yet this species has managed 2 and three generations each year. Here, with our short mild winters, we may see up to four generations. The potential for large infestations in a short time, with accompanying serious crop losses, is huge. Since California is responsible for a large percentage of US food crops, the potential for serious impacts to our national food supplies is significant.

Control of this pest is difficult at best. The nymphs of Brown Marmorated Stink Bug can be controlled on contact with some agricultural sprays but the adults are strong fliers that easily move into a previously controlled area, rapidly reestablishing the infestation. Orchardists in the Mid-Atlantic have had to apply up to 22 treatments during a growing season in order to maintain control. In some cases even this high level of treatment proves futile. The only things known to feed on these true bugs are domestic chickens and some predatory insects like assassin bugs and praying mantises. But these have proven to be of little impact. Currently the US Department of Agriculture is studying a tiny parasitic wasp from BMSB’s native range that may be an effective means of control. The adult female wasp lays her eggs in the eggs of the stink bug. The wasp larvae feed on the bug’s eggs killing them. The current USDA studies aimed at ensuring that the wasp doesn’t present a danger to native organisms should take about two years.

The adults are shield shaped, approximately 1.5cm long and the underside is white or pale tan, sometimes with gray or black markings. The legs and antennae are brown with faint white banding. The stink glands are located on the underside of the thorax, between the first and second pair of legs. If you believe you have seen a Brown Marmorated Stink Bug capture the specimen and submit it to your local county extension as soon as possible for identification.