In the 1986 science fiction thriller Aliens, a party of soldiers and advisors has an encounter on a far distant planet with the movie’s monsters. This encounter makes clear to them that these creatures are virtually unstoppable by ordinary means. The main character advocates that they “dust off” and nuke the entire area from orbit. “It’s the only way to be sure…”, she demurs. Some problems have easy solutions.
At Burpee’s Fordhook Farm outside of Philadelphia, with warmer weather at hand, the brown marmorated stink bug—Halyomorpha halys (BMSB)—is on the move again. BMSB is an alien, invasive insect native to deep western Asia that is thought to have been brought here on shipping crates from China sometime in the mid 1990s. BMSB was positively identified only in 2001, but it is a strong flier and good at hitching rides on cargo and vehicles and has rapidly spread from its point of entry in eastern Pennsylvania. It may not yet have resident breeding populations everywhere it’s been recorded, but so far it’s been spotted in 33 U.S. states and several Canadian provinces (see https://lh3.googleusercontent.com/-8hW06DporNY/TWqMR-Gd2PI/AAAAAAAAAGQ/DLYfuk2c2BI/s1600/BMSBasof24Feb2011v4_2.JPG).
The initial complaints about BMSB were home invasion. Looking for warmth as temperatures cooled in fall, they come indoors and make themselves at home—and a nuisance throughout winter. They will not damage structures or bite humans or pets, but there can be lots of them in a home. They seek places to hide—behind picture frames and in attic spaces. But on warm days particularly, they fly into windows and lights, drop onto dinner tables during meals, and stink when startled or killed. However, beyond the great nuisance factor, which should not be minimized, there’s an even bigger problem.
Entomologists at federal, state and private organizations all agree that BMSB populations will explode this summer in the mid Atlantic region. Peach generally suffers stink bug damage, and peach growers there are in for a tough summer. But peach growers will not be alone. Anyone trying to grow almost anything worth growing—apples, pears, grapes, berries, tomatoes, peppers, corn (sweet or field), soybean, hawthorn, butterfly bush, roses, redbud, dogwood, maple, basswood, catalpa, and elm (the list goes on)—is going to have a hard time of it. BMSB turns out to be a significant agricultural pest.
The brown marmorated stink bug, so called because of its marbled or streaked coloration, looks in size and form much like its North American cousins. As adults, their shield-shaped body is almost 0.7 inches long. They exhibit shades of brown or gray with mottling, and the antennae have alternating dark and light bands (for images see http://www.invasive.org/browse/subthumb.cfm?sub=9328).
Stink bugs are sucking insects that extract plant fluids by means of a proboscis that is inserted into fruit, stem, or leaf. They feed on sweet plant juice that is predigested by the enzymes they secrete that breakdown and kill plant tissue, which results in rotten or sunken areas where the feeding took place.
There are some 250 stink bug species that are native to North America, and three of them have traditionally been pests of peach and other fruit crops as well as some ornamental plants. But BMSB has an advantage over our native stink bugs: it is essentially invisible to North American stink bug predators. And because it has no natural enemies here and will feed on (apparently) almost any plant (60 species growing in North America have been indentified so far), its population is unchecked and it is expected to continue spreading to new habitats.
In homes, the best way to control BMSB is to keep it out in the first place. In older homes that are a little leaky, this may be next to impossible. But whatever ways there are to exclude it should be tried—sealing cracks around windows, doors, chimneys and siding; assuring that screens are intact; and removing window air conditioners as cool weather approaches are some examples. These stink bugs tend to congregate on south and west walls of structures in fall. Insecticides can be used around suspected entry points such as windows and doors. Scientists at Rutgers University have tested lots of insecticides against adult BMSB; they found that cyfluthrin, bifenthrin and deltamethrin were effective against BMSB in laboratory tests. Timing of insecticide application is important though. If used too early, the insecticide may breakdown; if applied too late, BMSB may already have invaded your house.
Once inside a house, BMSB should be removed by hand or by means of a vacuum. Use of insecticides inside a house is not recommended. This is because BMSB that die within walls or in other unreachable places invite a new infestation of pest in the form of dermestid or carpet beetles that will come to feed on the BMSB carcasses.
In the home garden, cyfluthrin, bifenthrin and deltamethrin are insecticides that gardeners can use on ornamentals and some vegetables. Follow warning labels, however, and check with county agricultural agents for more information. If the garden space is not too big or the infestation not too severe, there’s always hand picking. And there is a pheromone trap that has just become available (http://www.agbio-inc.com/index.html). It is said to “work” and to have been developed “…in close association with leading universities and the USDA/ARS.” This may well be a great product. And it is certainly worth trying, but traps for Japanese beetle (Popillia japonica) work well in attracting the pest but seem to attract more beetles than they capture, leaving the rest to feed in your garden. And killing BMSB by hand is a very unpleasant task: you have to squeeze them firmly and quickly before they spray. I know someone who got hit with the mildly acidic and horrid substance on the hand, wrist and forehead. Yuck!
The most important natural enemy of BMSB in northern China has recently been identified as the small solitary wasp Trissolcus halyomorphae. This wasp parasitizes the eggs of BMSB, affecting up to 70% of them and killing as much as 50% of the potential annual BMSB population. The wasp is currently being studied as a possible biological control agent for BMSB but is not now found in North America. Before it can be released here into nature, it must first be demonstrated that the wasp itself is not an invasive pest. It likely is not, and in the future, management of BMSB populations in and around commercial orchards and other large-scale agricultural operations will almost certainly combine a biological control agent, such as this Chinese wasp, with pesticides and cultural practices.
BMSB is a pest so recently introduced and identified here that scientists are still scrambling to determine the extent of the problem and to evolve solutions. “Nuking it from orbit” will obviously not be among the solutions, and it is not going away. What solutions ultimately settle out will likely be costly, drawn out, and imperfect.