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Pest Alert: Brown Marmorated Stink Bug

Apple growers should be on the lookout for a potential new pest. The brown marmorated stink bug (BMSB) is an invasive alien species that was introduced to Pennsylvania about 10 years ago. Since that time, it has spread and has now been reported in over 26 states. The BMSB is an excellent hitchhiker and is readily moved over great distances in cargo and vehicles. In Canada, the BMSB has not been found yet in any crops; however, this pest was intercepted in some shipments of imported goods coming into several provinces including Ontario. It is likely only a matter of time before this insect shows up in the field. The United States Department of Agriculture does not regulate BMSB. The Canadian Food Inspection Agency (CFIA) has not formally communicated their decision on BMSB, but since it has spread over such a wide area in the US and because it is not possible to control the pathways for introduction, it is very unlikely that this insect will be regulated in Canada.

Why worry about the BMSB? This insect has a very large host range that includes over 100 plant species, such as stone and pome fruit, berries, grapes, vegetables (corn, tomatoes, peppers), soybeans and edible beans, hardwood and ornamental trees, and woody shrubs. Extensive damage has been reported in commercial tree fruit in areas where this pest has reached high population levels. In apples, damage by stink bugs is easily confused with bitter pit (Figure 1).

Brown marmorated stink bug adults overwinter in sheltered areas that may include homes and other heated structures. As they can aggregate in large numbers, the BMSB has become a considerable nuisance pest for home owners where established. While the bugs do not bite humans, they will release a foul smell when handled or otherwise disturbed. Aggregation in artificial structures is not common among stink bugs, and is a behaviour that may provide an early warning that BMSB has established in Ontario.

Common stink bugs and other similar looking insects are easily confused with the BMSB, including species of brown stink bugs, rough stink bugs (common in orchards), western conifer seed bugs (which also end up in homes), and squash bugs. All of these bugs have obvious alternating light and dark pattern geometric described as being "checkered", a feature which may confuse the untrained eye. The BMSB is a relatively large stink bug (up 10 17 mm), with smooth / untoothed "shoulders" (edges of the thorax), and with two white bands on each antenna that are not found on other common stink bugs (Figure 2); this feature is obvious on adults and on nymphs.

Timely identification of this insect while populations are low will facilitate response and allow for the implementation of management strategies to limit damage to agricultural producers. We could use your help with the early detection of BMSB. If you find suspect damage or suspect stink bugs, please submit a sample to the University of Guelph Pest Diagnostic Clinic, the CFIA, the National Insect Collection in Ottawa (they have an identification service, see http://www.canacoll.org/NIS/NIS.html) or an OMAFRA office.

Figure 1. Feeding damage in apple may be confused with bitter pit.(Steve Jacos, Entomology, Penn State Univ.)

Figure 2. Late instar BMSB nymph. Note the obvious whit bands on the legs and antennae. (Gary Bernon, USDA APHIS, Bugwood.org)