Stink Bugs
Sink bugs are being talk about a lot this year, both in the Okanagan and at the Coast.
The questions is:
Are they Stink bugs or Western Conifer Seed bugs that are coming in our houses?
It is important to know your winter wanderers because western conifer seed bugs can be mistaken for brown marmorated stink bugs. One is native and the other is an invasive species and a significant pest of garden and agricultural crops.
In the Okanagan we are seeing mostly western conifer seed bugs. They can be annoying, unwanted, or repulsive, but they don’t bite or cause harm to humans or plants in the garden. They do not reproduce in our homes. Seed bugs do emit a strong piney small when they feel threatened, but seed bugs aren’t stink bugs.
The adult seed bugs are looking for overwintering sites in September and October. That’s why we are seeing them on our houses and in every little nook and cranny. Most of the time they find a spot under debris in our gardens or in the forest. When temperatures drop below freezing outside, we will start to see fewer of them. They are native to the US, now found in Canada and cause damage to cones of conifer trees.
Western conifer seed bugs aren’t something we have to trap in large numbers. If they are found inside your house, they can be easily caught with a paper towel or by hand and released outside. Fly swatters and vacuums work well too. The best action is to keep doors closed and ensure window screens don’t have any cracks in them. Seed bugs can also get into the house through small cracks in the walls, doors etc. So, sealing up your house works the best to keep seed bugs out.
The other species that is often talked about is the brown marmorated sink bug (BMSB). Downtown Kelowna is a ‘hot spot’ for this insect, and it is being seen in significant numbers in Coastal regions in BC. It is not found in other parts of Kelowna or the Okanagan in significant numbers. BMSB is coming into Canada in shipping containers, in wood, cargo and vehicles from Asia. Like seed bugs adults, BMSB adults emits a strong smell when threatened and hide in buildings as they seek warm overwintering sites.
BMSB is an invasive species and a pest of agriculture crops. They attack tree fruits, berries, grapes, vegetables, and ornamental plants. Ornamental hosts include tree of heaven, chokecherry, catalpa, boxelder, white ash, maple, English holly, and buckthorn. In British Columbia, they have been found on Asian pears, vegetables, and wild chokecherries. The adults and nymphs insert their mouthparts into the flesh of fruit and vegetables. This causes dark coloured lesions, pits, depressions, cat-facing, and gummosis, making the fruit unmarketable.
Brown marmorated stink bugs can be controlled in the same way that seed bugs are. However, it is not yet necessary to control their numbers in the Interior of BC. The numbers aren’t high enough to warrant the additional work and costs.
If present BMSB should be controlled. They can be trapped indoors by placing a dish of soapy water in a dark room with a light pointed at it. The stink bugs are attracted to the light and drown in the water. Some homeowners at the coast, where numbers are higher, are using these traps to catch BMSB. This type of trap is not needed for seed bugs.
Currently it is not recommended to spray either insect with any of the products registered for homeowner use and many aren’t effective. This is a new pest for Canada, and it takes time for Health Canada and companies to test the safety and efficacy of products and then to register them.
The ministry of Agriculture has found samurai wasps in Kelowna. These wasps do not sting people. They are an egg parasitoid which means they lay their eggs inside the eggs of BMSB and have the potential to be an effective biological control agent of BMSB (they parasitize 60-90% of BMSB egg masses). Samurai wasps are a natural control of BMSB in Asia and they have not been released into the US or Canada. The wasp is not considered an invasive species in Canada.
In the gardens in the Okanagan, it isn’t necessary to treat BSMB right now. Numbers aren’t large enough to cause significant concerns. When they do become a concern, row covers can be used to cover vegetables and many fruits to keep BSMB out.
To learn more:
Brown Marmorated Stink Bug (BMSB) Pest Alert - Province of British Columbia (gov.bc.ca)
Stop Brown Marmorated Stink Bug - StopBMSB.org
Brown Marmorated Stink Bug Management Guidelines--UC IPM (ucanr.edu)