The Brown Marmorated Stink Bug (Pentatomidae: Halyomorpha halys) is an introduced stink bug species from Asia that is spreading throughout the Mid-Atlantic United States, having been first collected in Pennsylvania in the fall of 1996 (Hoebeke and Carter 2003), with isolated populations occurring in Massachusetts, Mississippi, Ohio, Oregon, and California. It is native to South Korea, Japan, and eastern China, where it is a pest of tree fruit and soybeans. It has inflicted significant damage on fruit farms in the United States as well. (Hamilton 2009; Nielsen and Hamilton 2009) In 2007, this stink bug was reported for the first time from Europe (from several sites in the region around Zurich, Switzerland), suggesting that it may be spreading in Europe as well (Wermelinger et al. 2008)
Regularity: Regularly occurring
Type of Residency: Year-round
The Brown Marmorated Stink Bug (Halyomorpha halys) is native to South Korea, Japan, and eastern China, but has been accidentally introduced to North America, where it is spreading throughout the Mid-Atlantic United States (Pennsylvania, New Jersey, Maryland, Virginia), with isolated populations occurring in Massachusetts, Mississippi, Ohio, Oregon, and California. It has also been reported recently from Switzerland, at several sites in the region around Zurich, suggesting that it may be spreading in Europe as well (Wermelinger et al. 2008).
For a technical description of Halyomorpha halys (including the egg and each instar) and for details on distinguishing the genus Halyomorpha from other Old World genera, see Hoebeke and Carter (2003). Several dozen Halyomorpha species are known from Africa, Asia, and India (Hoebeke and Carter 2003).
In eastern North America, the only pentatomids that resemble Halyomorpha halys in overall size (12 to 17 mm) and dorsal coloration are species of the genus Brochymena. Brochymena species, however, have the juga each with a tooth on the outer side subapically and the pronotum with the anterolateral margins coarsely dentate. By comparison, H. halys lacks teeth on the outer juga subapically and the anterolateral margins of the pronotum are not dentate, but entire. (Hoebeke and Carter 2003)
In Europe, Halyomorpha halys might be confused with Holcostethus and Rhaphigaster nebulosa. In contrast to the 12 to 17 mm long Halyomorpha halys, Holcostethus are 9 to 10 mm in length and the front edges of the pronotum and the apex of the scutellum are pale. The head of R. nebulosa is quite regularly cone-shaped while that of H. halys shows a marked angle with a broadly rounded front. (Wermelinger et al. 2008)
Yang et al. (2009) described a new species of scelionid wasp, Trissolcus halyomorphae, that parasitizes the eggs of the Brown Marmorated Stink Bug in China, with observed parasitism rates of up to 70% or higher and an average annual rate of 50%. Because of the high parasitism rates and other biological features, this wasp appears to have good potential as a biocontrol agent. It appears to be the primary biological regulator of populations of Brown Marmorated Stink Bug in northern China (Yang et al. 2009) Native North American Trissolcus species apparently parasitize this stink bug in its introduced range in North America, but at a low rate (Nielsen and Hamilton 2009).
Life History and Behavior
The Brown Marmorated Stink Bug is univoltine in New Jersey and Pennsylvania (U.S.A.), with peak abundance from late July through early September, but if it becomes established in warmer parts of the United States it could have multiple generations per year, as it does in warmer parts of its native range. Minimum temperature thresholds for development of Brown Marmorated Stink Bugs studied in the United States are higher than reported from Japan, suggesting that U.S. populations may have originated in warmer parts of the native range, such as subtropical regions of China or India. (Nielsen et al. 2008; Nielsen and Hamilton 2009)
Overwintered adults emerge from hibernation sites in early spring. Mating and oviposition start about 2 weeks later. Sexually mature females usually mate more than once (as many as five times per day). A female mated only once can store enough sperm to lay eggs for nearly half her lifespan, but fecundity decreases in proportion to her age. The period of laying fertile eggs and fecundity increase with multiple copulations. Females deposit eggs on the lower leaf surfaces of host plants from May to late August. Egg clusters commonly contain 20 to 30 eggs, which hatch in 4 to 5 days. As with other pentatomids, H. halys has five nymphal instars. Emerging adults of the first generation are generally observed in early to mid-August. Development time from egg to adult is one to two months, depending on season and geography. (Hoebeke and Carter 2003 and references therein)
Evolution and Systematics
Molecular Biology and Genetics
Barcode data: Halyomorpha halys
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Halyomorpha halys
Public Records: 3
Specimens with Barcodes: 295
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Relevance to Humans and Ecosystems
The Brown Marmorated Stink Bug is a highly polyphagous horticultural and agricultural pest (Hoebeke and Carter 2003 and references therein). It is a pest of tree fruits in Japan and South Korea, particularly persimmons, apples, and pears. It is the dominant stink bug pest on South Korean non-astringent persimmons(Diospyros kaki) and Yuzu (Citrus junos). (Nielsen and Hamilton 2009; Yang et al. 2009 and references therein) In China, it has become a serious pest of soybeans, vegetables, and tobacco, as well as many forest and ornamental trees, being especially harmful to orchards. It attacks a wide variety of fruits, including pear, apple, peach, plum, cherry, pomegranate, common jujube, citrus, persimmon, mulberry, hawthorn, apricot, grape, kiwifruit, and strawberry. Adult Brown Marmorated Stink Bugs generally feed on the fruit, whereas nymphs feed on leaves, stems, and fruit. This stink bug is also reported to be a vector of Paulownia witches' broom disease, an extremely destructive phytoplasma disease of Paulownia trees in China. (Yang et al. 2009 and references therein)
Brown marmorated stink bug
Halyomorpha halys, also known as the brown marmorated stink bug (BMSB), or simply the stink bug, is an insect in the family Pentatomidae, and it is native to Korea and Taiwan. It was accidentally introduced into the United States, with the first specimen being collected in September 1998. The brown marmorated stink bug is considered to be an agricultural pest, and by 2010-11 has become a season-long pest in U.S. orchards.
The adults are approximately 1.7 centimetres (0.67 in) long and about as wide, forming the "shield" shape characteristic of other stink bugs. They are various shades of brown on both the top and undersides, with gray, off-white, black, copper, and bluish markings. Markings unique to this species include alternating light bands on the antennae and alternating dark bands on the thin outer edge of the abdomen. The legs are brown with faint white mottling or banding. The stink glands are located on the underside of the thorax, between the first and second pair of legs, and on the dorsal surface of the abdomen.
The brown marmorated stink bug is an agricultural pest that can cause widespread damage to fruit and vegetable crops. In Japan it is a pest to soybean and fruit crops. In the U.S., the brown marmorated stink bug feeds, beginning in late May or early June, on a wide range of fruits, vegetables, and other host plants including peaches, apples, green beans, soybeans, cherries, raspberries, and pears. It is a sucking insect, a "true bug", that uses its proboscis to pierce the host plant in order to feed. This feeding results, in part, in the formation of dimpled or necrotic areas on the outer surface of fruits, leaf stippling, seed loss, and possible transmission of plant pathogens.
The brown marmorated stink bug is more likely to invade homes in the fall than others in the family. The bug survives the winter as an adult by entering houses and structures when autumn evenings become colder. Adults can live from several months to a year. They will enter under siding, into soffits, around window and door frames, chimneys, or any space which has openings big enough to fit through. Once inside the house, they will go into a state of hibernation. They wait for winter to pass, but often the warmth inside the house causes them to become active, and they may fly clumsily around light fixtures.
The stink bug's ability to emit an odor through holes in its abdomen is a defense mechanism meant to prevent it from being eaten by birds and lizards. However, simply handling the bug, injuring it, or attempting to move it can trigger it to release the odor.
In the United States 
The brown marmorated stink bug was accidentally introduced into the United States from China or Japan. It is believed to have "hitched a ride" as a stowaway in packing crates. The first documented specimen was collected in Allentown, Pennsylvania, in September 1998. Several Muhlenberg College students were reported to have seen these bugs as early as August of that same year.
Other reports have the brown marmorated stink bug recovered as early as 2000 in New Jersey from a black light trap run by the Rutgers Cooperative Extension (RCE) Vegetable Integrated Pest Management program in Milford, New Jersey.  In 2002, it was again collected in New Jersey from black light traps located in Phillipsburg and Little York and was found on plant material in Stewartsville. It was quickly documented and established in many counties in Pennsylvania, New Jersey, Delaware, Connecticut and New York on the eastern coast of the United States. By 2009, this agricultural pest had reached Maryland, West Virginia, Virginia, Tennessee, North Carolina, Kentucky, Ohio, and Oregon. In 2010 this pest was found in additional states including Indiana, Michigan, Minnesota, and other states. As of November 2011 it has spread to 34 U.S. states.
2010 U.S. population increase 
Higher than normal numbers of stink bugs have been reported in the eastern half of the United States. The following are some of the possible reasons for the dramatic population increase:
- Stink bugs typically have four generations per growing season in Asia, and one after transplantation to the U.S., but an unusually warm and early spring and summer have apparently allowed them to produce two additional generations in this growing season in regions like Maryland and Northern Virginia. 
- The extra generations means that some states are seeing more bugs in more places than in previous seasons. Adults are living longer, depositing eggs longer and maturing more generations to lay even more eggs.
The higher than normal population has caused some of the following environmental problems:
- The insects have started attacking fruit and trees in orchards in southern and eastern Pennsylvania, which had not been seen in previous years.
- Bugs pierce the fruit’s outer surface and suck out juices while injecting saliva. The suction and saliva create a dimpling of the fruit’s surface, and rotting and corking of the flesh underneath.
- The fruit is not salable because of appearance although the dimpled area is not poisonous to humans.
- The bugs attack numerous types of plants—including tomatoes, soy beans, lima beans and sweet corn—but fruit show the damage more quickly and orchard owners monitor for damage more closely. Little is known about what these insects do in the wild.
Similarity in appearance to native species 
Easily confused with Brochymena and Euschistus, the best identification for adults is the white band on the antennae. It is similar in appearance to other native species of shield bug including Acrosternum, Euschistus, and Podisus, except that several of the abdominal segments protrude from beneath the wings and are alternatively banded with black and white (visible along the edge of the bug even when wings are folded) and a white stripe or band on the next to last (4th) antennal segment. The adult rice stink bug (Oebalus pugnax) is distinguishable from the brown marmorated stink bug by noting the straw color, the smaller size, and the elongated shape of the rice stink bug.
In China, Trissolcus halyomorphae, a parasitoid wasp species in the family Scelionidae, is a primary predator. This species is not currently present in the U.S., but is undergoing study for possible introduction by 2013. Several other species of the parasitoid wasp have been documented attacking stink bug eggs in a Virginia soybean field. Some species of spiders and praying mantises will attack adult stink bugs.
See also 
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