University of Maryland Extension

Brown Marmorated Stink Bug - Frequently Asked Questions

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What is the story on the brown marmorated stink bug (BMSB)?

The brown marmorated stink bug (Halyomorpha halys) is a new pest in North America. Adult bugs are 5/8” and dark mottled brown. The last 2 antennal segments have alternating light and dark bands. The exposed edges of the abdomen also have light and dark banding. They emerge from  overwintering sites from late March through June depending on location. They immediately begin to feed. Females lay clusters of light green, barrel-shaped eggs on the undersides of leaves from June to August. The young bugs (nymphs) are yellowish and mottled with black and red. Older nymphs more closely resemble the adults. There are 5 stages or instars. In Maryland we can have over 2 or more generations a year. 

What do they feed on and what kind of damage do they cause?

The host list is long and includes many ornamental plants, fruit trees, vegetables, and legumes. The nymphs or young stink bugs tend to feed shallowly, while the adults feed deeply into plant tissue causing more damage. Damage will vary depending on the plant. On leaves, it can appear as small stippled areas and/or necrotic areas. On fruit, there may be water-soaked lesions, pitting, dimples, catfacing, and/or depressed areas. Adult stink bugs can cause deep feeding injury in fruit such as apples making them unsalable. Damage on vegetables such as peppers and tomatoes appears as cloudy whitish areas in the fruit. On beans and okra, there will be wart-like growths and deformation or shriveling of the pods. Early stink bug feeding on corn results in incomplete kernel formation, while later feeding causes kernel collapse and brown discoloration. 

How do you manage them in the garden?

Check your local garden center or nursery for early ripening tomatoes (e.g. Early Girl) or determinate (short) varieties (e.g. Celebrity). It was widely reported in 2010 that the tomato cultivar Juliet was relatively resistant to feeding injury. Gardeners should become familiar with what the bugs look like in all life stages from egg to adult. Hand-pick and/or knock bugs into a container of soapy water to control them. In areas where populations are high, diligence is necessary because of constant migration into the garden from surrounding landscapes and wooded areas.

How do you keep them out of your house?

These stink bugs have also become a tremendous nuisance in homes and buildings as they seek shelter in the fall much like Asian lady bird beetles and boxelder bugs. Prevent them from coming in the home by sealing up cracks with caulk, use weather stripping around doors and windows, remove window air conditioners, and close all possible entry points. Inside shop- vacuum up the bugs and place in an outdoor trash receptacle. It should be noted that if many of them are squashed or pulled into a vacuum cleaner, their odor can be quite strong.

What insecticides control the stink bugs?

We do not recommend insecticides for controlling brown marmorated stink bugs because:

  • Most are ineffective
  • Some are broad-spectrum and will kill beneficial insects like honeybees and predators that eat pest insects, including BMSBs..
  • Use of broad-spectrum insecticides can lead to secondary pest outbreaks such as spider mites.
  • They pose human and environmental health risks.

Should you choose to try an insecticide to control the stink bugs read the label carefully. The plant (site) or the bug must be on the label! Follow all safety precautions.

What are researchers doing to help with the problem?

Very detailed studies on biology (including environmental cues for aggregation), control options, pheromone studies on pheromones, mass trapping, and biological control are currently being conducted by researchers at the USDA and Land Grant Universities. BMSB was introduced into this country without its natural enemies and therefore has no natural control mechanisms to keep populations in check. Biological control shows the most long term promise for eventual control/management of this pest. Research is underway to identify egg parasitoids that will aid in control of BMSB. Studies are being conducted at the USDA’s Biological Control Research laboratory and it is hoped that in approximately 3 years parasite releases will begin.

 

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