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Dear Ruth

Stink bugs…

Yikes they eat everything in sight.  Besides picking them off daily what can I do?  I have never seen so many!!

Dianne Markham—growing organically for 32 years

 

Dear Dianne,

There are almost 300 kinds of stinkbugs in the USA, and some of them are even helpful stinkbugs. In the upper southeast, four destructive stinkbugs are commonly found: Green Stink Bugs (Acrosternum hilare), Southern Green Stink Bugs (Nezara viridula), Harlequin Bug (Murgantia histrionica),and Brown Stink Bugs (Euschistus servus). But there IS a new stinkbug in town, and its reputation precedes it. The new stinkbug is called a Brown Marmorated Stink Bug (Halyomorpha halysStål) or BMSB. First identified in Pennsylvania, the BMSB is from Asia and apparently slipped through customs undiscovered in the late 1990’s. By 2010 the brown mamorated stink bug was causing severe damage to crops in most mid-Atlantic states, and has rapidly spread to 39 states, Washington, D.C., and Canada – posing serious threats to ornamentals, fruits, vegetables, and row crops, but they are also invading houses.

 

BMSB

Photo by USDA

What? Invading houses? Yuck! According to Virginia Tech entomologist Ames Herbert, “Here in northwestern Virginia…the stink bugs are my No. 1 home pest. The exterior walls of my house are black with them. A door or window can’t be opened (at any hour) without 4 or 5 flying inside.” They aren’t that bad in Western North Carolina, but I have discovered a few in my house. They do not sting or bite. They seek out warm places to over-winter. My personal approach is to squash them as soon as I spot them. One friend said she captured them in her house and threw them outside. But what do you think happens to stink bugs that get thrown outside? It’s simple. They find a mate and reproduce. With my apologies to any pacifists reading this article, lets try to eliminate brown marmorated stink bugs before they have a chance to reproduce. Here is an easy alternative to squishing them – whether outside in your garden or inside your home: just drop them in a jar of soapy water (yes, this will kill them rather quickly).

 

 

 

Generally, stink bugs are not very bothered by agricultural chemicals. In one studyabout stink bugs, less than 70% of stink bugs in test fields were affected by three different strong conventional insecticides and one organic insecticide (spinosad). This study did not look at the Brown Marmorated Stink Bug, but in a 2011 NPR article, Bob Black of Catoctin Mountain Orchard in Maryland states, “This one [BMSB] can actually play in it [insecticide] and eat it, and it won’t even kill it – that’s how tough this insect is.” Notably – in the unsprayed test fields in the same study – within three weeks nearly 50% of the southeastern stink bug eggs had been parasitized by wasps (wasps lay their eggs inside stink bug eggs and when the wasp eggs hatch, they feed on the stink bug eggs). Fortunately, a much lower rate (19%) of beneficial bugs were parasitized. Some studies have shown that localized wasps are adapting to the presence of BMSB and starting to parasitize BMSB eggs as well. Scientists are also studying an Asian wasp that parasitizes BMSB in its Asian homeland as a possible control for the BMSB in the USA.

BMSB2

Mature stink bugs inflict the most damage to plants by using their sucking mouth parts. Damage can range from mostly cosmetic to extensive and devastating. Check out these great pictures of BMSB instars (the Brown Marmorated Stink Bug’s development from egg to mature adult) so you recognize all stages of this bug. The elliptical whitish eggs are usually found in clusters of about 28 eggs. Squish the eggs when you discover them. The older the bug gets, the harder it is to eradicate, so be proactive with your control methods. According to my research…the BMSB will hide from you, they can fly up to two kilometers a day, and they over-winter. Please note item #7 below – that mulch is a habitat stink bugs enjoy. Pictured to the right is a Stink Bug Trap invented by Dr. Russell F. Mizell III of the University of Florida.

 

Controlling BMSB – Ideas from the University of Maryland Extension:

  1. Clean up plant debris after season, especially crucifers and legumes.  Tilling disrupts overwintering sites.
  2. Use row cover when possible, beginning in spring.
  3. Search for egg masses and crush. Handpick bugs.
  4. Bugs hide or drop when startled. Knock into a container with soapy water held underneath.
  5. A cloudy spot in fruit can be cut out and does not affect eating quality.
  6. Insecticidal soap or botanicals such as neem or pyrethrum are only effective on young nymphs. Adults are resistant even to highly toxic insecticides.
  7. Thick organic mulch provides desirable habitat for stinkbugs. Consider removing mulch or using plastic, fabric or rolled paper mulch.
  8. Many natural predators and parasitoids are still not enough to control them, but conserve beneficial predators by using only insecticides with a short residual.
  9. Thick-skinned cultivars may provide some resistance.

BMSB3I wrote a previous article about harlequin bugs which may be helpful to read and comes to similar conclusions

  1. Brassicas are a favorite food for stink bugs
  2. Stink bugs are hard to treat with anything.
  3. Any organic insecticide – such as safer soap, neem, or pyrethrin – must contact the insect’s body to kill the bugs, and should be sprayed late in the evening to protect bees and prevent plant burn.
  4. Molt-X (Azadirachtin) is an insect growth regulator that may be an effective spray but costs around $149. per pint, has a short shelf life, and will not work on adults.
  5. Be vigilant and proactive – act in egg stage, and when bugs are young.
  6. Keep garden area debris-free and weed-free to reduce habitat.
  7. Plant resistant varieties.
  8. Remove crop residues, and till in late fall to reduce overwintering of stink bugs.
  9. Maintain healthy plants with adequate water and fertilizer – so that they are less susceptible to insect damage.
  10. Provide habitat for beneficial insects

Some more useful links:

Stop Brown Marmorated Stink Bug Site:

http://www.stopbmsb.org/

Northeastern IPM Center, BMSB Working Group:

http://www.northeastipm.org/working-groups/bmsb-working-group/bmsb-information/

Other bugs that could be mistaken for BMSB

http://www.stopbmsb.org/stink-bug-basics/look-alike-insects/

Article from Dr. Jeanine Davis:

http://ncalternativecropsandorganics.blogspot.com/2013/05/updates-for-farmers-on-brown-marmorated.html

Report on Research/Control of Stink Bug

http://southeastfarmpress.com/management/natural-predators-tested-stink-bug-control

Mike Raupp, University of Maryland Extension, Video, Keeping Stinkbugs Out of Your House http://youtu.be/9Wp8cd_VQBA

Disposing of Stink Bugs via Toilet Flushes/Soap Spray Video:

http://youtu.be/XoFDTPhzgZM

 

So Dianne, your practice of daily picking the stink bugs off your plants is actually a pretty good solution, combined with some of the cultural ideas from UMD Extension in the list above. Keep your eyes open for the eggs and destroy them. Plants that harbor beneficial insect populations could be helpful as well. It sounds like the Brown Marmorated Stink Bug will become an increasing and hard-to-deal-with challenge.

 

Thank you for your question,

Ruth

 

Ask Ruth © 2013 Ruth Gonzalez & Organic Growers School

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Ruth Gonzalez is a former market farmer, gardener, local food advocate, and founder of the Tailgate Market Fan Club where she blogs at http://tailgatemarketfanclub.wordpress.com. In her job at Reems Creek Nursery, Ruth offers advice on all sorts of gardening questions, and benefits daily from the wisdom of local gardeners.

 

 

Ruth Gonzalez

Ruth Gonzalez

Ruth Gonzalez is a former market farmer, current gardener, and local food advocate. She has written numerous local food and gardening articles, blogs about local food, and writes the “Ask Ruth” Gardening Column for Organic Growers School. In her job at Reems Creek Nursery, Ruth offers advice on all sorts of gardening questions, and benefits daily from the shared wisdom of local gardeners. She has a special affection for clouds and finds delight in the natural world at every turn. Read more from Ruth at her blog: http://tailgatemarketfanclub.wordpress.com/