The weather has warmed and stink bugs are currently emerging from their overwintering locations in our attics and walls. As always, stink bugs are unwelcomed visitors in our homes — but his year the stinky pests are wanted by the University of Maryland.
Stink bugs can be collected in plastic food containers. Dively suggests throwing a piece of apple in the container to give the bugs food and poking holes in the container’s lid to give the bugs fresh air.
If you collect more than several dozen bugs, contact the research lab on the College Park campus by email (firstname.lastname@example.org). So far, one household has collected more than a thousand stink bugs for the research effort. And you thought your house had the bugs bad!
This past week, I had the opportunity to interview Galen Dively about his stink bug research and a some tips for home stink bug prevention. Below is my interview:
Kevin Ambrose (KA): Can the suspected virus be used to combat the stink bug in the future?
Galen Dively (GD): We’re not sure yet if the cause of death is a virus or a fungus. Virus sprays are often not effective against bugs but once we identify the cause of the colony collapse then research will be done to see if there are other methods to combat the stink bug.
KA: Do you think the past two cold winters thinned the population of stink bugs in the Washington area?
GD: Yes, although this invasive species of stink bug is from a region in China that has similar climates in the Washington area, the unusual cold temperatures have undoubtedly reduced the overwintering success of adults in sheltered areas outside of dwellings. Besides overwintering inside dwellings, we know they also overwinter under the bark of the standing or fallen dead trees in wooded areas. In fact, the sheltered situations outside is probably the main site of overwintering in many areas.
KA: We’ve received information from our CWG readers that the stink bugs are worse in the counties to the west of Washington. Where is the stink bug epicenter in our region?
GD: The highest populations of stink bugs are located in Central and Western Maryland, Northern Virginia, the northeastern counties of West Virginia. Infestations are highest in houses and other dwellings surrounded by trees and close to soybean fields where they tend to feed late in the fall to build up their energy stores for overwintering.
KA: Why do you think the stink bugs are not a major problem on the Eastern Shore where there is plenty of agriculture?
GD: This insect prefers landscapes that are fragmented with woodlots, agricultural fields (particularly corn and soybean), and dwellings. At a larger scale, high temperature is a limiting factor. The landscape on the Eastern Shore is less fragmented, larger cleared areas with contiguous crop fields, fewer woodlots and dwellings per land area; and summer temperatures are higher on the coastal plain area than in the Piedmont area.
KA: What are the major focus areas for your stink bug research?
GD: There are several research focuses as follows:
1) The female stink bug during egg laying smears fecal material on the eggs which contain a specific bacteria that the immature nymphs need for normal development and survival; we consider this as a weak link in its life history. Studies are ongoing to investigate ways to disrupt the development of the immature nymphs.
2) Rearing the stink bug is an essential requirement for ongoing research, so studies are focused on preventing colony crashes due to disease and the development of an artificial diet for the stink bug.
3) In its native land (China), the stink bug is maintained under control by natural enemies, mainly tiny wasps that parasitize the eggs. We have similar parasitic wasps that attack our native stink bugs and our studies are focused on whether these natural enemies will shift over to the invasive species of stink bug. In order to rear these natural enemies and conduct research on their potential as natural control agents, our studies need stink bug egg masses from the colony.
4) In addition, several studies are conducted during the growing season to evaluate chemical, biological, and cultural control measures for the stink bug.
KA: I know that stink bugs are attracted to home gardens in the summer. What vegetables and plants do the stink bugs prefer?
GD: They prefer tomatoes, peppers (all types except the really hot Thai varieties), okra, sweet corn, green beans, and eggplant. Less preferred are the vegetables in the cabbage family and cucurbits (cucumber, melons, pumpkin, and squash). They also feed on large and small fruit crops.
KA: Do you have any tips for making a home stink bug-proof, or at least reducing the number of bugs that enter a house?
GD: Caulk all cracks and spaces that can serve as entry portals, make sure there are no holes in windows screens and screen covers of vents in the attic, weather stripping around doors to prevent entry, and seal openings around window AC units.
KA: Do you foresee any new plans or methods to combat the stink bug with insecticides, stink bug eating wasps, or traps?
GD: The parasitic wasps probably have the greatest potential for long-term control of this invasive stink bug. USDA has brought back several species from China and are currently studying their potential non-target effects in quarantine populations, before they are released if allowed at all. One exotic species from China has been carefully tested for about three years, and USDA was about ready to petition for its release; but to our surprise, this species was found occurring naturally at Beltsville, Maryland late last summer, apparently introduced accidentally in containers, probably the same way the stink bug came into our country. Now, extensive surveys will be conducted this summer to determine if this parasitic wasp survived the winter and is spreading its distribution range, and will it impact the stink bug population.
For gardeners and organic farmers, the insecticides that are available to these users are not effective on the stink bug. We are investigating the use of attractive trap crops such as sunflower, grain sorghum and even okra. The idea is plant these crops close to or around a cash crop to divert stink bugs away from the cash crop.
Traps are being used to monitor flight activity but so far have not proved to be effective trap and kill strategies. In fruit production, there is promise of using pheromone traps in a ‘baited’ tree at the edge of the orchard to concentrate invading stink bugs in one spot and then kill them with an effective insecticide. We do have a number of good conventional insecticide products that are available to commercial farmers, but not homeowners for gardeners unless they have a pesticide application license.