Be On Lookout For New Plant Pest In Iowa

An insect known as the brown marmorated stink bug is a serious plant pest that was first found in the United States in 2002. Now it has been confirmed in Iowa, but ISU entomologists don't know what the economic importance of it is here yet.

Published on: Mar 10, 2011

The brown marmorated stink bug , which has the scientific name 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 the Iowa State University Extension Plant and Insect Diagnostic Clinic and the Iowa Department of Agriculture and Land Stewardship confirmed that a single dead specimen of this pest 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 this bug travels readily in shipping containers and with people. Iowa State University Extension entomologist Erin Hodgson and Laura Jesse of the ISU plant diagnostic clinic at Ames provide the following information.

This is an insect that can do serious damage to crops

This insect has 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 United States. 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 the brown marmorated stink bug in Iowa. For a complete host list (pp.30-33) and detailed information on this insect see the USDA Risk Analysis.

This insect 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. 

It can be a household pest too, like boxelder bugs and lady beetles

If the brown marmorated stink bug 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 brown marmorated stink bug.

It is this habit of spending the winter in buildings that has aided the dispersal of brown marmorated stink bug by movement in containers and vehicles. If you have observed any insects similar to the brown marmorated stink bug in your house this winter please submit a sample (at no charge) or send a digital photo to the ISU Plant Insect and Disease Identification Clinic at Ames. "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," says Jesse.

Submitting insect samples: For information on submitting a sample, the ISU PIDC has instructions for submitting insect samples to the clinic and an information page on the brown marmorated stink bug

General biology: The brown marmorated stink bug is an invasive insect that was recently discovered in North America, Jesse explains. It was first identified in fall 2001 in Allentown, Penn.; 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).

This insect 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," says Jesse.