A fall visitor: Brown marmorated stink bug

Stink bug adult on the hood of my car. Photo: HJB

After running errands Saturday morning, I noticed the insect above on the hood of my car. My apologies for the poor photo quality, but it was the best I could manage on the fly with my cell phone camera. This morning, another greeted me inside my living room window, leaving behind the trans-2-decenal and trans-2-octenal to prove it. From the glimpse I got, it appeared to be a brown marmorated stink bug (BMSB, Halyomorpha halys). This invasive insect has temporarily taken the place of bed bugs as the go to pest, garnering attention from the New York Times, Washington Post, and even NPR's Science Friday. A multi agency work group has been established to study BMSB biology, management, and regulation.


Why has BMSB generated so much interest this fall? For two main reasons:
1. Large populations have caused extensive damage in agricultural crops, and
2. They aggregate in structures in large numbers in the fall, becoming a nuisance pest.


First detected near Allentown, PA in 1998, BMSB has been present in the United States since then, but this summer their populations increased dramatically in the mid Atlantic. BMSB has been present in North Carolina since at least 2009, but has not reached the damaging levels observed in Maryland, north east Virginia, and Pennsylvania this year.

BMSB damage on an apple. The corky masses below the skin are distinctive of stink bug feeding. Photo: Penn State Extension

From mid summer through fall, BMSB has caused significant damage in the mid Atlantic to apples, peaches, caneberries, corn, and soybeans, to name a few of the crops it has been recorded from. Stink bugs, including our native species, the brown stink bug (Euschistus servus), green stink bug (Acrosternum hilare), and southern green stink bug (Nezara viridula), are difficult to manage with insecticides. Typically, broad spectrum materials, such as pyrethriods, carbamates, and organophosphates have been used to manage stink bugs, but may of these have the potential to create unintended consequences, like reducing natural enemies. Treatments for BMSB did not fit with carefully developed IPM programs for tree fruit in Maryland and Virginia, and resulted in greater pesticide use.


Stink bugs (native and non native) are emerging pests in many cropping systems due in part to their difficulty to control and in part to the increased number of insecticides (or other tools) that target a narrow range of organisms. For example, stink bugs are now a key pest of cotton due to the widespread adoption of Bt varieties that control caterpillars. Foliar applications of broad spectrum insecticides targeting caterpillars used to also control stink bugs but are no longer needed. The same scenario could apply to systems that have switched to other newer insecticides (i.e. Entrust, Delegate, Intrepid, Coragen, and many others) from broad spectrum materials.


The second reason BMSB has generated such wide attention is its tendency to aggregate in structures in the fall, much like the multicolored Asian lady beetle and another recently introduced bug, the "kudzu bug". All of these insects are native to roughly the same part of the world, China, Japan, and Korea, so it is possible that this fall aggregation behavior is associated with insects from these areas.


What should growers do if they suspect BMSB is present on their farm? Contact your cooperative extension agent to confirm identification and for management recomendations.


What should homeowners do if they suspect BMSB are present in their yards or homes? If BMSB are presents in your yard, there are few control measures that will be effective, and the most sustainable strategy is to tolerate injury to plants. If stink bugs are entering your home, seal entry points well (think of it as an entomological energy audit) and vacuum up the insects, disposing of your vacuum bag.

More information

Move over bed bugs; the stink bugs have landed - New York Times

Invasion of stink bug has homeowners, farmers seeking relief - Washington Post

Stink bug invasion - Science Friday

BMSB Monitoring - Rutgers University

BMSB Fact Sheet - Penn State University
Kudzu bug - IPM in the South

A different story at the Sandhills

After yesterday's visit to the Upper Mountain Research Station, I was eager to check my spotted wing drosophila (SWD) traps at the Sandhills Research Station today.  My first stop at the station was the caneberry breeding plots.

Caneberry seedling plots at Sandhills Research Station.  Photo: HJB

Raspberries are grown at Sandhills not because they do well here but because most raspberries cannot tolerate high heat.  The plots here are intended to screen breeding material for heat tolerance traits that will be used to develop raspberries that can be grown in hot summers.  In other words, most raspberries are not happy at the Sandhills.

We began catching SWD adults at the Sandhills on 11 August 2010 and trap captures peaked on 18 August.  See trapping data here.  Dates are in ordinal days; see here to convert ordinal days into calendar dates.  There were no blackberries present at this time, few peaches were remaining, and no larvae were found in fruit.  No flies were captured during the month of September, and one fly was caught last week.

SWD and raspberries have a lot in common in terms of temperature tolerance.  Both like mild weather and, at least according to current literature for SWD, do not reproduce in hot weather.  I suspect that the record heat this summer may have limited SWD's initial spread through North Carolina, but now as fall temperatures cool, we may see more flies and more maggots.

There were a few raspberry plants with fruit, and most of what I observed did not contain visible larvae.  I did find one, otherwise perfectly sound fruit, that contained one early instar larva.

Early instar maggot (center of image), likely spotted wing drosophila, in a red ripe raspberry at the Sandhills Research Station, Jackson Springs, NC. Photo: HJB

Because this larva was so small, I collected a sample of other raspberries from the field and will be holding these to determine if any others contain SWD larvae.

Ripe and overripe raspberries collected to determine the presence of SWD larvae at the Sandhills Research Station. Photo: HJB

 So, why do we have a large amount of infested fruit at Upper Mountain and very little (apparently) infested fruit at Sandhills?  Fruit availability differs between these two site this time of year; Upper Mountain has strawberries, caneberries, and grapes ripe and open to infestation while Sandhills only has a few remaining raspberries.  But why did the Sandhills infestation not take off when the hundreds of peach trees at the station were loaded with fruit?  The flies were not present in high numbers at the height of peach season, but I also think climate played an important role.  The Sandhills are in the hottest part of North Carolina, and peach season is during the hottest part of the year.  This may have limited the spread of SWD into the Sandhills this summer.  Now that the fly is present and reproducing, it will be interesting to see what next summer holds.  We will be there to find out.


Sponsored by the Southern Region Small Fruit Consortium, Project 2010 E-01.

SWD appears with a vengeance at Upper Mountain Research Station

Male D. suzukii on raspberry leaf, Upper Mountain Research Station.  Photo taken 30 September 2010 by Absalom Shank, NC State Horticulture Department

Yesterday, I spent the day at the Upper Mountain Research Station near Laurel Springs confirming the first spotted wing drosophila (Drosophila suzukii) larval infestation in North Carolina.  Spotted wing drosophila (SWD) is a potentially devastating invasive pest of soft skinned fruit which has been present in North American since late 2008.  See here for more background.  Blackberry, raspberry, and strawberry research plots are heavily infested.  SWD were first observed on 30 September in high tunnel primocane fruiting raspberry plots by Absalom Shank, research technician in the NC State Horticulture Department.

Up until last week, no larval SWD had been observed in North or South Carolina, despite the fact that adults have been captured in high numbers.  This is likely due to the fact that most of our trap captures occurred after the majority of susceptible host fruit had been harvested.  It is likely that larvae have been present but in low enough numbers that they escaped detection.

The first thing I did after arriving at the station was to place 6 SWD traps in 3 of 4 high tunnels, where the highest number of flies had been observed.  These tunnels contain primocane and floricane fruiting blackberries and raspberries. Three of the traps were baited with apple cider vinegar, and 3 were baited with a yeast and sugar mixture, as are being used in our regional monitoring program.  Within 20 minutes, the first adults appeared at the apple cider vinegar baited traps.  A total of 4 flies were captured in 3 hours.

Apple cider vinegar baited SWD trap in primocane fruiting blackberry tunnel.  Photo: HJB

Male SWD at apple cider vinegar baited trap entry.  Photo: HJB

SWD larvae were observed last week in fruit from guard plants and caneberry seedling plots, both of which are not regularly harvested.  This week, larvae were found in trial plots, which are harvested twice per week, so flies are not restricted to unharvested plantings.

Fallen raspberries in breeding plots.  These fruit can harbor SWD populations. Photo: HJB

Adult SWD were readily observed and collected in high tunnel plots (and the most of those were in primocane fruiting raspberries), but were not as numerous in outside plots.

Female SWD on ripe raspberry fruit in a high tunnel.  Photo: HJB

Primocane fruiting blackberries in high tunnel.  Photo: HJB.

Primocane fruiting raspberries outside. Photo:; HJB

Many fruit in raspberry breeding/seedling plots were heavily infested, which is not surprising considering that these plots have never been harvested.  Most of the fruit collected contained multiple larvae.

Ripe yellow raspberry from breeding plot.   This single fruit contained 5 SWD larvae.  Photo: HJB

Strawberry plots at the station also contained large numbers of SWD larvae.  Because it was very windy, adult fly presence could not be confirmed in these plots.  Flies which appeared to be SWD females were present, but these are more difficult to sight identify than males.  The fruit damage observed, however, was consistent with SWD.  Sound appearing fruit contained multiple maggots when cut open.  Larvae were collected to rear out adults.

Strawberry containing multiple SWD larvae.  Photo: HJB

These strawberry plots had also not been harvested for several months and contained sound, rotting, and decomposed fruit, all of which are attractive and suitable for SWD larval feeding.

Strawberry plots containing heavily SWD infested fruit.  Photo: HJB

Strawberries with recently laid SWD eggs were also found.  These fruit appeared sound except for a slightly abraded area where the eggs were.

Strawberry fruit with slightly abraded area containing SWD eggs.  Photo: HJB

Enlarged view of SWD eggs.  Photo: HJB

I collected several adult flies and numerous infested fruit to bring back to laboratory to start a research colony.  These insects will be used to test host fruit preference, monitoring tools, and control strategies.  This afternoon I am heading to check my traps at the Sandhills Research Station and check the caneberry breeding plots there for larval infestation. Update: I visited the Sandhills Station today.  See here for a summary of what I found.


SWD Monitoring
We have been monitoring SWD in NC, SC, and VA for 5 months and have detected flies in Montgomery County, NC; Lee County, NC; Randolph County, NC; Davidson County, NC; Edgecombe County, NC; Saluda County SC; Spartanburg County, SC; and Lexington County, NC.  We can now add Ashe County, NC to that list.

Small fruit and tree fruit growers should be aware that SWD populations are present at potentially damaging levels and should carefully monitor their plantings for adult and larval presence.  Caneberry growers with primocane fruiting berries and strawberry growers with fall fruiting or day neutral plantings should be especially aware.  Adult traps can be constructed from plastic containers or bottles (see here for a description of trap construction and here for videos demonstrating trap construction and use).  Sticky cards for use in traps can be obtained from a variety of sources.  We get ours from Great Lakes IPM.  Male SWD are readily distinguished from other flies by their spotted wings.  Females are more difficult to distinguish, and growers should consult their county extension agent for identification confirmation if males are not present.  See here for examples of SWD and non SWD flies on sticky traps.  Traps should be checked at least weekly.

Growers should also monitor fruit for larval infestation.  Large larvae will be visible in fruit, but small larvae may not.  Larvae can most easily be detected via the "fruit dunk" method.  Fruit are gently crushed and floated in sugar water.  After several minutes, larvae float to the surface and can be counted.   See here for a video and here for a description.  A hand lens may be necessary to observe small larvae.  It is important to remember that many native Drosophila feed on rotting fruit.  Observing infestation in relatively sound fruit and confirming adult presence minimizes the likelihood that you will confuse SWD with native relatives.

SWD Management
Sanitation is extremely important in managing SWD.  In areas where SWD is present, all ripe fruit should be removed from the field or plants should be treated with insecticide regularly, with the interval depending upon the material used.  Unmarketable fruit should be destroyed or removed from the site.  Composting may not be sufficient to kill SWD larvae and may attract adults to rotting fruit.  This presents a challenge to fruit breeding activities at research stations and will need to managed with care.

SWD populations in the western US (California, Oregon, and Washington) appear to respond well to a number of insecticides, which is encouraging news.  I am preparing a document listing the registered materials that are effective against SWD by crop and will have this available early next week.  Growers who have confirmed SWD should contact their county cooperative extension agent or myself for management recommendations.  It is especially important to rotate insecticides used to treat SWD to minimize the likelihood of resistance development.

More information
OSU SWD Website
Spotted Wing Drosophila Updates - WSU Mount Vernon Research Center
Strawberries and Caneberries - Blog by Mark Bolda (UC Farm Advisor)
NC Small Fruits IPM SWD Posts



Sponsored by the Southern Region Small Fruit Consortium, Project 2010 E-01.

Fall NC Entomological Society Newsletter

October is a busy month for the North Carolina Entomological Society! Read all about our recent and upcoming events in the NCES Fall Newsletter.

More information
Fall 2010 Newsletter - NCES

UNC system facilities are 'in a mess' - Education - NewsObserver.com

The Entomology Department is also housed in Gardner Hall. Although my lab is in another building, it's in no better condition.

More information

UNC system facilities are 'in a mess' - Education - NewsObserver.com

North Carolina Entomological Society seeks outstanding teachers!

Do you know a teacher (K-12) who uses insects in creative ways in their classroom?

If so, the North Carolina Entomological Society wants to know! We are seeking outstanding teachers who use entomological tools in their classroom, whether to teach students about the wonderful world of insects or to assist in the teaching of other concepts. Last year, we recognized 3 teachers, Susan Dixon (Western Alamance Middle School, Elon), Kathleen M. Dorn (Hunter Huss High School, Gastonia), Teresa Garrou (Hudson Elemenary, Hudson), one each for elementary, middle, and high school.

Teachers can nominate themselves or others. Strong applications typically include examples of of the insect learning activities used. This can include lesson plans, photos, example assignments, and more. Applications are due to me either via mail (NC State University, Campus Box 7630, Raleigh, NC 27695-7630) or email (hannah_burrack@ncsu.edu) by October 15, 2010. Application information can be found here. This year's awards will be presented at the NCES banquet on November 5th at the JC Raulston Arboretum and comes with a monetary award to be spent on school supplies. Travel and registration to the banquet are included in the prize, and we hope winners will be able to join us to be recognized.

More information
NCES Outstanding Teacher Award Application
North Carolina Entomological Society

SWD trapping update - Identification overview

One male spotted wing drosophila (circled) and 3 non SWD. Trap from Davidson County, NC. Photo: HJB

Drosophila suzukii (spotted wing drosophila) trap captures are increasing throughout the Carolinas. Last week, SWD were confirmed from our monitoring site in Davidson County, NC, and we continue to catch flies at 7 other locations in NC and SC. The table below summarizes these locations and the total flies detected to date. See here for links to trap capture data for all of the southeast monitoring locations.

Site	Date of first capture	Total flies to date
Davidson County, NC	8/24/2010	19
Edgecombe County, NC	7/30/2010	1
Lexington County, SC (Site 1)	7/30/2010	6
Lexington County, SC (Site 2)	8/6/2010	19
Spartanburg County, SC	8/13/2010	4
Saluda County, SC	7/2/2010	5
Randolph County, NC	7/27/2010	9
Montgomery County, NC	8/11/2010	17

In addition to SWD, several other flies have been caught in the traps, many of which can be confused with SWD. The image above includes 1 male SWD with clearly visible wing spots (circled) and 3 other flies which could be confused with SWD. The image below notes the key characters to distinguish between these 3 flies.

Non SWD flies. Left: fly with "cloudy" cross veins (cross vein circled). This cross vein will not be cloudy in SWD wings. Center: fly with spotted abdomen. SWD will have no discrete spots along the abdomen. Photo: HJB

Also found in yellow sticky traps have been flies with 3 spots on each wing (below).

Drosophilid fly with 3 wing spots (indicated by blue boxes). Photo: HJB

In addition to flies which may potentially be confused with male SWD, there are also flies which may be difficult to distinguish from female SWD. The most important female feature is the prominent ovipositor (below). The ovipositor can be hard to distinguish when insects are on yellow sticky traps, but can be teased out and still appears different than that of any other female fly.

SWD ovipositor. Fly captured in Edgecombe County, NC. Photo: HJB

Female SWD on yellow sticky trap, ovipositor indicated by blue box. Photo: HJB

Ovipositors of non SWD females are much smaller and lack the dark brown teeth on the anterior margin.

Non SWD females. Note much smaller ovipositors that lack dark marginal teeth (click to enlarge). Photo: HJB

More information

Washington State University SWD ID Guide



Sponsored by the Southern Region Small Fruit Consortium, Project 2010 E-01.