Category Archives: Insect

Insect update for Aug. 17, 2017

Corn earworm moth captures in the black light traps ranged from 2 to 45 moths per night; brown marmorated stink bug catches ranged from zero to 2.6 per night. Here are the data tables: BLT_17_Aug_2017

In our corn earworm (bollworm) vial tests, we are averaging 39% moth survival, with 832 moths tested to date.

Insect update for Aug. 10, 2017

Black light trap captures of corn earworm/bollworm ranged from 5 to 78 moths per night this week. Brown marmorated stink bug captures ranged from zero to 2 per night. Here are the data tables: BLT_10_Aug_2017

Resistance monitoring of corn earworm/bollworm shows that this season in Suffolk, an average of 39% of moths survived the 24-hour exposure period to the pyrethroid, cypermethrin.

Plant Bug Update – 4 August 2017

Twenty-three representative cotton fields in eight Virginia counties were scouted weekly for mean plant bug density. Data for the July 17th to August 3rd sampling period is represented in the distribution map below (follow link to view). Red dots on the map represent fields that have averaged at or above the spray threshold for plant bug during the sampling period. Plant bug densities for multiple fields has increased substantially since the last update in mid-July. Nineteen of the 23 sampled fields have reached the spray threshold at least once this season since sampling began in late-June. Plant bugs are present in every county sampled and are likely present in at least low numbers in all cotton growing counties in the state. Therefore, we recommend scouting your cotton fields regularly for plant bug.

The spray threshold for plant bug in Mid-Atlantic cotton is eight plant bugs (i.e., adults and nymphs) per 100 sweeps in addition to square retention below 80 percent. We recommend conducting four to eight random 25-sweep samples throughout each field. Once flowering begins, we recommend continuing sweep net sampling and also looking for dirty blooms (pictured below) or sample dime to quarter size-bolls from 25 random plants for internal feeding damage (e.g., warts, stained lint, punctures). Spray treatment may be warranted if dirty blooms and or internal damage exceeds 15 percent and plant bugs are also active in the field. Please refer to the Virginia Cotton Production Guide (pg. 23)  or Pest Management Guide (sect. 4, pg. 88) for spray recommendations if spray threshold is reached.

“Dirty bloom” indicative of plant bug feeding.

When viewing the distribution map in full-screen mode, click on the left arrow icon to view map legend. Click on individual fields represented by colored dots on the map to view mean plant bug density for the sampling period as well as total mean density for the season. Mean plant bug densities were calculated by sampling four sweet net samples (25 sweeps per sample) and four drop cloth samples across each field. Total adults and nymphs in a single visit were totaled and averaged for each visit within the sampling period.

View full-screen distribution map

Plant bug distribution map for the July 17th to August 3rd sampling period.

 

Insect update for Aug. 3, 2017

Black light trap catches of corn earworm (aka bollworm) moths increased at most reporting stations, ranging from 5 to 58 per night this week. The pheromone traps at Suffolk also caught about 20 moths per night. Mike Arrington reported that he was seeing cotton fields (Bt and conventional) very close to egg threshold for bollworm in Suffolk and Southampton Counties.

Brown marmorated stink bugs ranged from zero to 1.7 per night. The data tables for corn earworm and BMSB are here: BLT_3_Aug_2017

Corn earworm moth survival in the cypermethrin vial tests was 36% for the week, and 40% for the seasonal average (to date).

Insect update for July 27, 2017

Corn earworm/bollworm moth captures in the black light traps increased this week, with averages ranging from 2 to 65 moths per night. Suffolk and Hanover had high numbers. Brown marmorated stink bugs ranged from zero to 10 per night across our reporting stations (high numbers in Hanover). More details can be found in the tables here: BLT_27_Jul

Be sure to scout your fields to keep aware of your pest situation. The 2017 Virginia Cooperative Extension Field Crops Pest Management Guide contains thresholds, sampling procedures, and products/rates for soybean (pages 4-61 to 4-76), peanut (pages 4-77 to 4-86), cotton (pages 4-87 to 4-100) and other crops. There is also an online threshold calculator for corn earworm in soybean

Results (to date) from Dr. Taylor’s corn earworm survey of field corn are as follows:  Accomack= 29% infested ears; Northampton=38%; Henrico=37%; Chesapeake=19%; Dinwiddie=19%; Greensville=19%; Prince George=20%; Southampton=53%; Sussex=26%; Amelia=18%; Lancaster=4%; Northumberland=7%; Richmond County=4%; Westmoreland=6%; and Franklin County=46% infested ears.

Insect update for July 20, 2017

This week, our black light trap operators reported a range of zero to 8.5 corn earworm/bollworm moths per night and zero to 2.7 brown marmorated stink bugs per night. The tables are in this pdf file: BLT_20_Jul_2017

The corn earworm/bollworm pyrethroid resistance monitoring program is averaging about 36% moth survival. These are pheromone trap-collected moths from Suffolk, Virginia. The pyrethroid is cypermethrin at 5 micrograms per vial.

Virginia Cooperative Extension ANR Agents, Virginia Tech personnel, interns, and others have started our annual field corn survey for corn earworm/bollworm larvae. It can be an indicator of the pressure that we’ll see in other crops (e.g., soybean) when the moths emerge and fly out of corn fields. We’ll have a full report in the beginning of August (including data from many more counties), but here are the average ear infestations from those surveys already completed (based on sampling 50 ears per field, 5 fields per county): Accomack=29%; Henrico=37%; Southampton=53%; Amelia=18%; Westmoreland=6%.

 

Plant Bug Distribution Map

Twenty-three representative cotton fields in eight Virginia counties were scouted weekly for plant bug abundance and square retention. Data for the June 28th through July 13th sampling period is represented in the distribution map below (follow link to view). We will continue to post updates to the map through peak plant bug abundance in cotton. Sweep net and drop cloth samples were taken for each field to account for sampling bias associated with sweep net sampling towards adult captures and drop cloth sampling towards nymphal captures. When sampling cotton fields for plant bugs, look carefully for nymphs (pictured below). Since nymphs are flightless, they may spend more time feeding in an isolated area and cause more damage than adults because their movement in and out of fields is limited. The action threshold for plant bug in Mid-Atlantic cotton is generally eight plant bugs (i.e., adults and nymphs) per 100 sweeps in addition to square retention below 80 percent.

Plant bug nymph feeding on weedy host, buckhorn plantain (Plantago lanceolata).

When viewing the distribution map in full-screen mode, click on the left arrow icon to view map legend. Click on sampling labels on the map to view square retention and number of samples taken from each site. Mean plant bug densities were calculated by sampling four sweet net samples (25 sweeps per sample) and four drop cloth samples across each field. Total adults and nymphs in a single visit were totaled and averaged for each visit within the sampling period.

Click here to view full-screen distribution map

Plant bug distribution map in Virginia cotton sampled from 28 June to 13 July 2017.

Insect report for July 13, 2017

Virginia Cooperative Extension ANR Agents and Virginia Tech faculty/staff have started up their black light traps to monitor corn earworm moths (aka bollworm) and brown marmorated stink bugs for the season. CEW and BMSB catches have been low in the black light traps; however, our pheromone traps in Suffolk, VA are catching moderate numbers of CEW moths–averaging about 5 per night. We tend to pick up more CEW moths in the pheromone than in the black light traps during this time of year. Dr. Taylor’s cypermethrin vial tests are showing about 35% of CEW moths surviving the 5 microgram rate (the moths were collected from the Suffolk pheromone traps). Watson Lawrence reported 26 brown stink bugs in his Chesapeake black light trap this week.

Corn earworm and fall armyworm trap catch numbers in Virginia – Week of July 10, 2017

 

Corn earworm larva in sweet corn.

Corn earworm and fall armyworm are two important pests of a number of agricultural crops in Virginia.  Sweet corn, in particular, is extremely vulnerable to attack by the larvae (or caterpillars) of these moth pests.  Monitoring moth catch numbers in pheromone-baited traps can help IPM decision-making.  See at the end of this post the Action threshold for spraying insecticides on sweet corn based on corn earworm trap catch.  In general trap catch less than 1 per night means relatively low pest pressure and sprays can probably be spaced 5-6 days apart during silking.  However, a catch of >1 or >13 moths per night means moderate and high pest pressure, respectively and a more frequent spray interval is justified.

In 2017, we are monitoring these pests on sweet corn farms in 11 different counties in Virginia.  Moth Trap Catch Data are being recorded by:  Katlyn Catron & John Few (Montgomery Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Virginia Beach); Kenner Love (Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk  (Westmoreland Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.)

Here are the trap catch results (moths per night) for several locations around Virginia for this week (note we do not have data for all locations):

Region County Field CEW  moths/night FAW moths/night
Eastern Shore Accomack ESAREC 1.1 0
Eastern Shore Virginia Beach Pungo 1 1.6 0
Eastern Shore Virginia Beach Pungo 2 3.9 0
Eastern Shore Northampton Bridge Tunnel 6.6 0
Eastern Shore Northampton Capeville 1 3.6 0
Eastern Shore Northampton Capeville 2 0.0 0
Eastern Shore Northampton Eastville 0.6 0
Eastern Shore Northampton Nassawaddox 1.0 0
Piedmont Amelia Field 1 2.7 0
Piedmont Hanover Field 1 2.1 0
Piedmont Hanover Field 2 1.0 0
Northern Neck Westmoreland Field 1 3.0 0
Shenandoah Valley Rappahannock Field 1 1.0 0
Shenandoah Valley Frederick Field 1 2.3 0
Shenandoah Valley Frederick Field 2 3.5 0
New River Valley Montgomery Whitethorne 1.9 0
New River Valley Montgomery Wall field corn 1.1 0
New River Valley Montgomery Wall sweet corn 20.8 0

 

Action threshold: Number of Corn Earworm Moths Caught in Pheromone trap
Per Day Per 5 Days Per Week Spray Interval for sweet corn
<0.2 <1 <1.4 No Spray
0.2 – 0.5 1.0 – 2.5 1.4 – 3.5 6 Day
0.5 – 1.0 2.5 – 5.0 3.5 – 7.0 5 Day
1.0 – 13.0 5.0 – 65.0 7.0 – 91.0 4 Day
>13.0 >65.0 >91.0 3 Day