The Halyomorpha halysalso called the brown marmorated stink bug (BMSB), is an invasive insect that was first reported in the United States in Allentown, Pennsylvania in the 1990s. In 2010, this insect caused over $37 million in damage to apples alone in the eastern states.In Alabama, BMSB was also first reported in 2010 and has now been established in all 67 counties. The insect has continued to expand its invasion into Europe, Eurasia, and South America (Chile), making it one of the most aggressive invasive species with a global impact.
Several previous studies and reports have provided information on this insect since it was found in Alabama. Yearly records of the insect’s population are valuable for decision-making, both to predict periods of risk and to determine the threshold number of pests that cause economic damage. Since May 2024, for example, integrated pest management specialists have monitored this insect and several others in Central and North Alabama to determine their movement and numbers. This information is expected to provide growers with the current pest situation and the potential risks to several crops.
In North Alabama, monitoring was done at the People’s Patch, a mixed-produce farm in Huntsville. The farm is a collaborative project between the District 6 Madison County Commission Office and Alabama A&M University.
The Central Alabama site is the Chilton Regional Research & Extension Center in Clanton, Alabama. Dual panel BMSB traps are installed in okra and tomato plots in Huntsville and among peaches in Clanton. Currently, data is only available at the Huntsville site (see Table 1). The Chilton site data will be available in the next report.
Table 1. Number of BMSB captured in traps in North Alabama
Note: Traps were set up on June 15, 2024 and checked weekly.
| Sampling Date | Trap 1 (border) | Trap 2 (border) | Trap 3 (interior) | Trap 4 (interior) | Total |
|---|---|---|---|---|---|
| June 22 | 14 | 10 | 8 | 4 | 36 |
| July 29 | 36 | 42 | 25 | 15 | 118 |
| August 5 | 20 | 31 | 37 | 19 | 107 |
| August 12 | 17 | 22 | 9 | 4 | 52 |
| August 19 | 9 | 10 | 5 | 7 | 37 |
| TOTAL | 96 | 115 | 84 | 49 | 344 |
BMSB Description
The adult BMSB is about 12-17 mm (0.66 inches) long. The adult is a mix of brown, dark red, and black on the dorsal surface. The ventral side is cream-colored, punctuated with metallic green markings on the ventral thorax. There are key characteristics that differentiate the BMSB from other stinkbugs with similar coloration. These include the presence of white bands on each antenna. In addition, there are no humeral (shoulder) spines, but alternating dark and light bands are found on the margin of the abdomen. The insect overwinters in human-made structures and migrates to find food during spring.
Biology, Ecology, and Behavior
In its native land, the BMSB can produce multiple generations during one season, but in the southern United States, it produces two generations. The female lays eggs in masses of an average of 28 individual eggs per egg mass. Egg masses when freshly laid are light green and mostly laid underside of leaves or fruiting structures. The egg mass is usually laid on the underside of leaves. Before the eggs hatch, they turn white. Incubation takes three to five days depending on season and temperature.
Newly hatched insects have black heads, red eyes, and reddish-orange abdomens with black markings. After hatching, the first instars (insects in the developmental stage) cluster and feed on remnants of the egg cases before dispersing to look for other food sources. The first instar remains around the egg cases until they molt to the second instar. The insect undergoes five instar developmental stages that take about 32 to 35 days to develop from egg to adult.
The BMSB is a polyphagous insect because it feeds on many plant species from different families — the adult and nymph feed on similar plants and plant parts. The insect has been found on several crop and non-crop plants. They prefer plants that produce succulent reproductive and vegetative structures, such as fruiting bodies, buds, and pods. Several studies indicate peaches, apples, filbert nuts, pears, wheat, grapes, field corn, soybeans, sorghum, and many vegetable crops, such as sweet corn, tomatoes, peppers, peas, okra, and eggplants are among the most economically important crop species. They are also hosts for H. halys. The BMSB prefers certain species of plants to others, often at different times during the growing season.
Reports indicate that the insect currently feeds on more than 100 different host plants. On landscapes, they choose plants based on availability. During the early part of the season, they are mainly found on early fruit and pod-bearing annual and perennial crops, such as peaches, okra, peppers, tomatoes, and many others. As the season progresses, they will shift to other available fruit, field, and vegetable crops. BMSB reasons for choosing certain plants is not well understood but it may be because they prefer those plants to others, as well as availability. However, their preferences are being studied to help humans understand their movement within different landscapes.
Stink bugs feeding on okra plants.
Monitoring the BMSB is necessary to determine pest management strategies. After several years of laboratory and field experiments, the clear double-sided sticky panel traps and BMSB dual lures have emerged as the most widely used monitoring tools for the BMSB. The lures and traps were tested mainly in apples and peaches in the mid-Atlantic region and were made available commercially.
Feeding incisions by adults and the second through the fifth nymphal stages are very difficult to detect. An early attack on plants leads to premature fruit abortion in some fruit. Detection of BMSB damage is difficult during later stages, often going unnoticed until fruit shows symptoms of cat-facing. To detect BMSB damage, the whole fruit or pod needs to be checked. For the fruit to be inspected, it must be sliced. BMSB damage can also be detected by shaking tree branches and plant parts early in the morning and by visual inspection of the hiding places of diapausing adults. In the summer of 2024, we recorded high numbers of BMSBs in okra.
Like most insect pests with similar behaviors to the BMSB, no single management strategy has been able to control it effectively. Effective control of BMSBs depends on the integration of different control methods. Currently, three main approaches are identified to be promising in controlling BMSBs in an integrated manner. These IPM components are mainly cultural control through proper farm sanitation, biological control, and application of reduced-risk insecticide. These approaches are suitable and effective but continue to be investigated for improvement.
In peaches and apples, the control of this insect is based on the application of insecticides at the border or edge rows since the BMSB is known as a border-driven pest which means they are likely to stay at the borders of most crops during initial movement from overwintering sites. These include the use of insecticide applications based on degree-day accumulation and trap numbers, biological control, and cultural control.
Although the BMSB is a border-driven pest, there could be a spillover into the interior of the crop when their numbers are high. Because of this border-driven behavior studies conducted in peaches and apples have shown that border application of insecticides will control this insect if their presence in crops is detected early.
Several studies have been conducted to determine the contribution of natural enemies to control this and other insects. Thus far, a comprehensive list is available for all the natural enemies that attack BMSBs in the field. The natural enemies include predators and parasitoids (mainly wasps). Currently, the most effective natural enemy is the parasitic wasp Trissolcus japonicus also called the Samurai wasp. This wasp attacks the eggs of the BMSBs and can cause mortality of about 10 percent. However, some studies have reported between 25 percent and 85 percent egg parasitism. This is significant and if the wasp can be managed well it can reduce BMSBs significantly.
The wasp was brought into the country for evaluation, but some were in fields in Maryland in 2015. Since then, the wasp has been found in many other states and efforts are still underway to investigate its effectiveness in controlling the BMSB. Another related wasp species T. basalis was reported to attack fresh BMSB eggs in Alabama. Yellow sticky traps in peaches and other host plants detect the presence of the wasps that attack BMSBs. Additional information will be provided later.
Other Natural Enemies
Other BMSB natural enemies at various stages include the following:
- Natural enemies of BMSB eggs. Spined soldier beetles, big-eyed bugs, Asian lady beetles, jumping spiders, earwigs, ground beetles, lacewing larvae, and pirate bugs.
- Nymphal natural enemies. Tachinid fly, spined soldier bug, lacewing larvae, spider, assassin bug, and Astata bicolor wasps.
- Adult natural enemies. Tachinid flies, praying mantis, web-building spiders, and assassin bugs.
The BMSB continues to be a major pest of many fruits and vegetables in Alabama. High numbers begin to build in mid-July to August when most host plants are fruiting or developing pods. Any attempt to control the insect should consider trap numbers. An acre of a plot should have a minimum of six traps. One trap should be installed at each border and two traps in the interior. Management requires planning even before planting starts in spring. Several insecticides have been tested in the past to determine their effectiveness.
Check the label to ensure that every product you use is approved for the crops you grow.
Contact your local county Extension office or search www.aces.edu for more information on the brown marmorated stink bug and other crop pests.
