The brown marmorated stink bug (BMSB, Halyomorpha halys) is an invasive pest that was accidentally introduced from Asia into Pennsylvania in the 1990s. Its first detection in North Carolina was in Forsyth County in 2009, and it has since spread rapidly throughout the piedmont and mountain regions of the state. The coastal plain has had fewer occurrences during this period, although the insect has appeared in isolated locations. As of February 2016, it had been confirmed in 69 of NC’s 100 counties. For information on dealing with BMSB around the house, see our FAQ page.
Although BMSB can be a destructive pest to a wide variety of crops, it usually establishes itself first in urban landscapes, roadside vegetation, and structures that provide attractive overwintering sites. This has been the case in North Carolina, with most early reports coming from property owners in urban areas between Raleigh and Asheville (the I-40 corridor) who have experienced BMSB “invasions” in late summer. Sightings in home gardens and on commercial farms have increased from extremely isolated reports in 2010 to widespread occurrences in 2015. In general, the pest has not yet caused the extensive agricultural problems experienced in the mid-Atlantic states, but it is on track to reach similar levels as local populations become further established.
Life cycle in North Carolina
Brown marmorated stink bugs overwinter as adults in human-made structures, standing dead trees, and other sheltered places. In April and May, these adults leave the protected areas and move into nearby woods where they mate and lay eggs on suitable host plants. By June or July the eggs have hatched and 1st-generation BMSB nymphs and adults begin entering nearby agricultural fields, generally preferring fruits and vegetables early in the summer and moving to soybeans later in the season. Under ideal conditions (warm temperatures and favorable hosts), a second generation of adults may be produced. As days become shorter in early August, adult BMSB cease laying eggs. In September, adults begin to disperse to overwintering sites, including homes and other structures, and by early October most individuals have entered their overwintering site. The month of September, when adults are aggregating on homes, is usually when invasions to new areas are first observed.
What’s being done?
Since 2011, NC State University has been part of a collaboration of over 50 scientists working on the biology and management of BMSB in the US. During that time we have introduced emergency measures to minimize crop damage, developed monitoring traps and attractants, gained a clearer understanding of the BMSB life cycle, and identified many of the wild plants that BMSB use to complete their development. We have also begun to identify native and non-native predators and parasitoids of BMSB, which perhaps hold the most promise for controlling the insect in the future.
Despite the short-term effectiveness of current control methods, they are not sustainable. Broad-spectrum pyrethroids and neonicotinoids have reduced the severity of BMSB damage in many crops, but they have also increased production costs and disrupted IPM programs, resulting in greater risk to non-target organisms and secondary pest outbreaks.
The focus of BMSB research has therefore shifted toward finding management strategies that can be used over the long term. Projects that North Carolina researchers are pursuing and will continue to pursue in the next few years include:
Studying BMSB phenology and host plant availability in different regions of North Carolina. To aid growers in anticipating BMSB invasions in their crops, and to provide guidance on specific locations and habitats within the state where BMSB is most likely to be a problem, studies are being conducted to determine the effect of temperature and host plant suitability on BMSB populations in different regions of NC. The highly aggregated distribution of BMSB in different ecoregions of North Carolina suggests that biotic and abiotic factors specific to these regions are important population regulation mechanisms. We are currently examining the effect of temperatures on both overwintering ecology and survivorship during summer months, and how host plant availability affects population density.
Identify natural enemies and incorporate them into management programs. Biological control has the potential to permanently suppress BMSB populations over a large landscape scale, something that isolated insecticide applications to crops cannot accomplish. In its native range of Asia, BMSB is not a major pest, partly because of small parasitic wasps (parasitoids) that parasitize and destroy large numbers of BMSB eggs. To date, research has indicated that native parasitoids in our region, as well as native predators such as katydids, jumping spiders, earwigs, and lady beetles, have only a modest effect on BMSB populations. Future research will focus on understanding which natural enemies are most effective, where they most commonly occur, and how management practices can enhance their activity in North Carolina agricultural systems.
We are also participating in a regional effort to monitor the spread of the native Asian parasitoid Trissolcus japonicus. This wasp is a highly effective parasitoid of BMSB eggs that was detected in 2015 in Maryland and northern Virginia, as well as Washington State. It is anticipated that this parasitoid will naturally disperse to other areas. This parasitoid is also being studied in quarantine at the USDA, and it is hoped that release permits will be soon be issued to accelerate the establishment of this biological control agent in a wide geographic area.
Optimize trap designs and develop models for their use. Very effective pheromone attractants and Tedders-style (black pyramid) monitoring traps have been developed for BMSB over the last five years. Despite their effectiveness, they are large, cumbersome to use, and not well-suited to all cropping systems. Further research aims to identify alternative trap styles (such as sticky cards and small pyramids) that are equally effective, as well as develop correlations between the numbers of BMSB captured in traps and the amount of damage appearing in crops. The goal is to develop a simplified trapping system whereby trap captures can be used as thresholds to dictate the need for insecticide use in different cropping systems.
Increase the number of pesticides available for BMSB control, and refine their use. Insecticides will remain a critical component of BMSB management for the foreseeable future, and pyrethroids and neonicotinoids are currently the most effective materials available. However, frequent use of these broad-spectrum chemicals is not compatible with IPM programs, and poses the potential for resistance development among BMSB populations. As new materials with new modes of action are developed, they will be lab- and field-tested for both efficacy against BMSB and minimal impact on natural enemies.
Report a sighting
Since 2011, NC State University has been collecting information about BMSB occurrences through an online survey. If you live in NC and have seen BMSB, please complete the survey here.
Frequently asked questions
Click here for the most common concerns.
Visit our lab on the web
The bulk of BMSB research in NC is conducted by the Walgenbach Lab at the Mountain Horticultural Crops Research and Extension Center in Mills River.