By Laura Jesse, Plant and Insect Diagnostic Clinic and Erin Hodgson, Department of Entomology
The brown marmorated stink bug, (BMSB), Halyomorpha halys, is a serious plant pest and household invader that has been making its way around the United States for the past decade. Recently Iowa State University Extension Plant and Insect Diagnostic Clinic (ISU-PIDC) and the Iowa Department of Agriculture and Land Stewardship confirmed that a single dead specimen of BMSB, was collected this February in Cedar Rapids, Iowa. This is the first confirmation of this pest in Iowa. However it is not known if this find indicates an established population or an isolated individual as BMSB travels readily in shipping containers and with people.
The brown marmorated stink bug submitted to the PIDC in 2011. This single dead insect was collected this February in Cedar Rapids, Iowa. The striped antennae, abdominal stripes and pale underside are characteristic of this insect. Photos by Donald Lewis.
Damage to crops
BMSB have been recorded causing economic damage to plants as far back as 2002 in Pennsylvania (where they were first detected), but in 2010 severe damage to fruit and vegetable crops were reported in the northeast. This insect has a wide host range that includes field crops like soybeans and corn, fruits and vegetables -- including apples, grapes, peaches-- and also ornamental trees and shrubs. New plant hosts will continue to be recorded as we learn more about this insect.
At this point, we do not fully understand the economic importance of BMSB in Iowa. For a complete host list (pp.30-33) and detailed information on BMSB see the USDA Risk Analysis.
BMSB feeds by puncturing plant tissues (leaves, fruits, stems) and sucking on plant juices with its beak, similar to aphids or leafhoppers. Damage can range from mild to severe and may appear as deformation, distortion, speckling, stunting, etc.
Two native stink bugs, the brown stink bug and the spined soldier bug, also occur in fields and gardens, and appear similar to BMSB. The spined soldier bug is a beneficial predator and the brown stink bug feeds on plants and is an occasional pest in Iowa.
The brown stink bug (left) and spined soldier bug (right) are similar to the BMSB but have more pointed 'shoulders' and lack the antennal stripes and clearly visible stripes on the abdomen.
If the BMSB behaves in Iowa as it has in other states then homeowners will be the first to note its presence as it is a fall accidental invader. Homeowners on the East Coast describe the stink bug invasion as worse than boxelder bugs and lady beetles, combined. Two other similar insects can also overwinter in homes — the boxelder bug and the pine seed bug. However both of these insects do not have the rounded shield shaped body of the BMSB.
It is this habit of spending the winter in buildings that has aided the dispersal of BMSB by movement in containers and vehicles. If you have observed any insects similar to the BMSB in your house this winter please submit a sample (at no charge) or send a digital photo to the ISU-PIDC. It is only through these reports that we can determine if we have a breeding population of these stink bugs in Iowa and where they are located.
Submitting insect samples
For information on submitting a sample to The ISU PIDC has instructions for submitting insect samples to the clinic and an information page on the brown marmorated stink bug.
The brown marmorated stink bug (BMSB) is an invasive insect that was recently discovered in North America. It was first identified in fall 2001 in Allentown, PA; though it is suspected it was on the east coast as far back as 1996. It was accidentally introduced, probably via shipping containers from Asia (no one brought it here on purpose).
BMSB spends the winter in the adult stage hiding in houses and other protected locations. In May the adults leave the hiding sites to feed on sap from plants. After mating, the females lay eggs in clusters of about 28 eggs on the undersides of leaves from June to August. A single female can lay up to 400 eggs. Eggs hatch into wingless immature bugs called nymphs that feed and grow for about five weeks before reaching the adult stage in late summer. We don't know how many generations per year are likely to occur in Iowa.
Laura Jesse is an entomologist with the Iowa State University Extension Plant and Insect Diagnostic Clinic; contact at firstname.lastname@example.org or by phone 515-294-5374. Erin Hodgson is an assistant professor of entomology with extension and research responsibilities; contact at email@example.com or phone 515-294-2847.