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Watch for Armyworms in Treasure Valley Lawns
All Crops Treasure Valley, Treasure Valley - Idaho, Treasure Valley Oregon
Armyworm, Order Lepidoptera: Family Noctuidae
Posted on: August 31, 2026 by Jemila Chellappa
A homeowner in Kuna recently reported large numbers of caterpillars in a lawn following accidental flooding, along with noticeable turf injury. The caterpillars appear consistent with armyworms, although species identification has not yet been confirmed. Homeowners and landscape professionals in the Treasure Valley are encouraged to inspect lawns showing unusual thinning, browning, or rapidly developing patches of damaged grass.
What to Look For
Armyworms are the caterpillar stage of noctuid moths and feed primarily on foliage. Depending on the species and age, larvae may be green, tan, brown, gray, or nearly black and often have distinct longitudinal stripes along the body. Mature larvae of some species may reach approximately 1½–2 inches long.
Armyworms get their name from their tendency, when populations are high, to move together across vegetation in large numbers.
- Numerous caterpillars in or near the turf
- Ragged, chewed, or closely clipped grass blades
- Brown or thinning patches that may initially resemble drought or heat stress
- Damage that appears to expand rapidly across the lawn
- Caterpillars hiding near the soil surface or in thatch during the day
- Increased bird activity in the lawn, which may indicate abundant caterpillars
Armyworms frequently feed during the evening and nighttime, so scouting around dusk or early morning may make them easier to find.
How to Scout
Inspect both the damaged turf and the green turf immediately bordering damaged areas. Separate the grass canopy and examine the thatch and soil surface for caterpillars.
A simple soap-flush method can also help bring turf-feeding caterpillars to the surface. The PNW Pest Management Handbook recommends a soap-flush scouting method for caterpillar pests of turfgrass. Apply a dilute solution of lemon-scented dish soap and water to a small section of turf and watch for several minutes for caterpillars emerging from the thatch.
If you find caterpillars, collect several specimens or take clear photographs showing the head and markings along the body for identification (https://www.uidaho.edu/extension/horticulture/insect-id).
Correct identification is important because armyworms can be confused with cutworms and sod webworms.
Management
Do not automatically treat simply because caterpillars are present. Armyworms have many natural enemies, including predatory insects, parasitic wasps and flies, and naturally occurring pathogens. Unnecessary broad-spectrum insecticide applications can disrupt these beneficial organisms.
For lawns with limited injury, continue scouting and maintain appropriate turf health. Avoid excessive irrigation or prolonged saturated conditions and manage excessive thatch where present.
If caterpillars are numerous and turf injury is actively expanding, management may be warranted. Biological insecticides containing Bacillus thuringiensis (Bt) can be useful against young caterpillars, and some spinosad products are also available for caterpillar management. Effectiveness depends on larval size, application timing, and whether the product is labeled for the intended turfgrass site.
Because many armyworm larvae are most active after dark, applications targeting actively feeding larvae are generally most effective during the late afternoon or evening.
Before applying any pesticide, confirm the pest and read and follow the pesticide label. The application site such as residential turf must be listed on the product label.
Why Scout Now?
Armyworm populations can develop quickly, and larger larvae consume substantially more foliage than younger larvae. Early detection provides more time to confirm the pest, evaluate the amount of injury, conserve natural enemies, and determine whether treatment is actually necessary.
Treasure Valley homeowners and landscape professionals who notice large numbers of caterpillars or rapidly developing turf damage are encouraged to scout and document what they are seeing.
Resources: University of Idaho Extension, Integrated Pest Management of Armyworms (BUL 1063) https://verso.uidaho.edu/esploro/outputs/report/IPM-of-Armyworms/996749725401851 and the Pacific Northwest Pest Management Handbooks https://pnwhandbooks.org/insect/hort/landscape/common/landscape-cutworm-fruitworm-armyworm
Psyllid captures climb; two psyllids from last week Lso positive
Potato All Locations
potato psyllid
Posted on: August 27, 2026 by Tasha Stanzak
• This week we received traps from 38 of the 55 fields that we are monitoring; many fields have now undergone vine kill.
• We captured a total of 281 psyllids spread across 23 fields.
• Captures were from the following counties: Canyon, Owyhee, Elmore, Jerome, Twin Falls, Cassia, and Minidoka.
• Of the 116 psyllids captured last week, two of them from Canyon County tested positive for Lso.
• For psyllids captured this week, we expect to have results on Lso incidence next week.
Overall psyllid captures continue to be relatively high, and captures per trap were notably higher this week than for the same time during the previous several seasons. Thankfully, Lso incidence has been relatively low for the most part, though there have been some positives over the last two weeks in Canyon County. The increased abundance of psyllids this week is also somewhat localized, with most psyllids captured in Canyon, Elmore, and Twin Falls counties. We urge growers to keep their IPM programs going, especially for areas that might be at slightly higher risk. In our research with Russet Burbank, tubers still have some risk of showing ZC symptoms in storage if infection occurs within 1-2 weeks before vine kill.
More information on management of potato psyllids and ZC can be found here:
https://www.uidaho.edu/extension/food/ipm/ag-pests/psyllids
To view the weekly data by site in the old spreadsheet format: https://tinyurl.com/potatopsyllid
Please visit the Idaho Pest Monitoring Dashboard, for graphical summaries of our psyllid captures from 2020 through the current week and an archive of this year’s weekly updates as the season progresses: https://idahopestmonitoring.org/
August 20, 2026 – Psyllid captures still relatively high; one psyllid from last week Lso positive
Potato All Locations
potato psyllid
Posted on: August 20, 2026 by Erik Wenninger
- This week we received traps from 35 of the 55 fields that we are monitoring (the remaining fields should be delivered to us early next week).
- We captured a total of 119 psyllids spread across 16 fields.
- Captures were from the following counties: Canyon, Owyhee, Elmore, Twin Falls, Cassia, and Minidoka.
- Of the 140 psyllids captured last week, one of them from Canyon County tested positive for Lso.
- For psyllids captured this week, we expect to have results on Lso incidence next week.
- We received traps late from one field from last week; those traps captured 3 psyllids. We expect to have results for those psyllids next week as well.
Overall psyllid captures continue to be relatively high, with captures being similar to those observed at this time in 2020 (the last time we had relatively high captures at this time). Risk of ZC continues to be moderate to low this year given this combination of moderately high psyllid captures and relatively low Lso prevalence. Much of the psyllid pressure continues to be focused in the Treasure Valley, especially Canyon County, and we did find one “hot” psyllid in this area last week. Relatively few psyllids have been captured in our Magic Valley sites, though we did see a slight uptick in captures in Twin Falls County. Psyllid captures often peak near the end of the season, likely in relation to dispersal from fields that are undergoing vine kill. We urge growers to keep their IPM programs going for areas that might be at slightly higher risk.
» https://idahopestmonitoring.org/
» https://tinyurl.com/potatopsyllid
» https://www.uidaho.edu/extension/food/ipm/ag-pests/psyllids
Psyllid captures slightly higher this week; one psyllid from last week Lso positive
Potato All Locations
potato psyllid
Posted on: August 13, 2026 by Tasha Stanzak
• This week we received traps from all 55 fields that we are monitoring.
• We captured a total of 140 psyllids spread across 23 fields.
• Captures were from the following counties: Canyon, Owyhee, Elmore, Gooding, Jerome, Twin Falls, Cassia, Minidoka, Bingham, and Bannock.
• Of the 92 psyllids captured last week, one of them from Twin Falls County tested positive for Lso.
• For psyllids captured this week, we expect to have results on Lso incidence next week.
• We received one field from last week late; those traps captured 3 psyllids. We expect to have results for those psyllids next week as well.
Overall psyllid captures were slightly higher than last week, and captures were similar to those observed at this time in 2020 and 2021 (the last time we had relatively high captures). Risk of ZC continues to be moderate to low this year given this combination of moderately high psyllid captures and relatively low Lso prevalence. Psyllid captures often peak around late July to August, so we will have to see whether captures climb next week. Much of the psyllid pressure continues to be focused in the Treasure Valley. Relatively few psyllids have been captured in our Magic Valley sites. Though we have found scarcely any psyllids in the Upper Snake sites, we did capture 4 psyllids in that region this week.
More information on management of potato psyllids and ZC can be found here:
https://www.uidaho.edu/extension/food/ipm/ag-pests/psyllids
To view the weekly data by site in the old spreadsheet format: https://tinyurl.com/potatopsyllid
Please visit the Idaho Pest Monitoring Dashboard, for graphical summaries of our psyllid captures from 2020 through the current week and an archive of this year’s weekly updates as the season progresses: https://idahopestmonitoring.org/
2026 Idaho Association of Plant Protection - Annual Meeting and call for topics
All Crops All Locations
General Announcement related to Agriculture
Posted on: August 10, 2026 by Kasia Duellman
Idaho Association of Plant Protection 2026 Annual
Meeting
The 2026 Idaho Association of Plant Protection (IAPP) annual meeting will be held November 4-5 at the Herrett Center at the College of Southern Idaho. The IAPP meeting is open to anyone interested in learning more about plant protection. Topics will cover all aspects of plant protection including entomology, nematology, weed science, and plant pathology. 4-6 ISDA pesticide credits and CEUs are anticipated.
Registration is $30 ($20 for students). The fee is the same if you attend one or both days of the program.
More information can be found here:
https://millerresearch.com/event/2026-idaho-association-of-plant-protection/
If you have any questions, please contact the 2026 co-chairs:
- Mitchell Bauske (mitchell.bauske@bayer.com) – Industry co-chair
- Kasia Duellman (kduellman@uidaho.edu) – University co-chair
» https://millerresearch.com/event/2026-idaho-association-of-plant-protection/
Psyllid captures slightly lower this week; all psyllids from last week Lso negative
Potato All Locations
potato psyllid
Posted on: August 6, 2026 by Erik Wenninger
- This week we received traps from 54 of the 55 fields that we are monitoring.
- We captured a total of 92 psyllids spread across 23 fields.
- Captures were from the following counties: Canyon, Jerome, Twin Falls, Cassia, and Minidoka.
- Of the 123 psyllids captured last week, none of them tested positive for Lso.
- For psyllids captured this week, we expect to have results on Lso incidence next week.
Overall psyllid captures were slightly lower than last week, and captures were similar to those observed at this time in 2020 and 2021 (the last time we had relatively high captures). Thankfully, no Lso was detected in psyllids last week. Risk of ZC continues to be moderate to low this year given this combination of moderately high psyllid captures and relatively low Lso prevalence. Psyllid captures often peak around late July to August, so we will have to see whether captures climb next week. Much of the psyllid pressure continues to be focused in the Treasure Valley. Relatively few psyllids have been captured in our Magic Valley sites, and scarcely any over the season in our Upper Snake sites.
More information on management of potato psyllids and ZC can be found here: https://www.uidaho.edu/extension/food/ipm/ag-pests/psyllids
To view the weekly data by site in the old spreadsheet format: https://tinyurl.com/potatopsyllid
Please visit the Idaho Pest Monitoring Dashboard, for graphical summaries of our psyllid captures from 2020 through the current week and an archive of this year’s weekly updates as the season progresses: https://idahopestmonitoring.org/
» https://idahopestmonitoring.org/
» https://tinyurl.com/potatopsyllid
» https://www.uidaho.edu/extension/food/ipm/ag-pests/psyllids
2026 University of Idaho August Field Days and other events
All Crops All Locations
General Announcement related to Agriculture
Posted on: August 4, 2026 by Kasia Duellman
Please mark your calendars for the following events organized by University of Idaho Extension faculty and staff and forward to all who may be interested:
UI Parma Field Day
August 13
Free Registration: 7:15-8:00 AM (MDT), including breakfast, posters and displays
8:00 AM - 12:00 pm (MDT): Tour and speaker presentations
Tour includes onion, hops, sugar beets, beans, potatoes, pollinators, apples, field and orchard tours.
CCA and pesticide credits have been requested for this event.
Contact: Gina Day (gday@uidaho.edu) 208-795-5350
UI Aberdeen Field Day
August 19
Free Registration: 8:30-9:00 AM (MDT)
9:00 AM - 12:00 PM (MDT): Tour and speaker presentations
Tour includes potatoes, mustard, small grains
1 ISDA pesticide credit, 2 CCA credits
Contact: Kasia Duellman (kduellman@uidaho.edu) or Chad Jackson (chadj@uidaho.edu)
More information: https://sites.google.com/uidaho.edu/extensionseedpotato/events
UI Ag Talk Tuesdays
Last session for 2026: August 18 - Ag Economic Outlook with Dr. Pat Hatzenbuehler
11:00 AM - 12:00 PM (MDT)
Free registration link (required to attend): https://uidaho.zoom.us/meeting/register/xJRvquC7T66Czb_qpW0A_A#/registration
More information: https://www.uidaho.edu/extension/events/ag-talk
Ag Talk Tuesday YouTube channel: https://www.youtube.com/playlist?list=PL6g6ZYcM47s85ASnhBlMHbFMD-x-zAGt6
UI Fresh Pack Potato Symposium
Nov. 17-18 at Canyon Crest Event Center in Twin Falls
Contact: Gustavo Teixeira (208-423-6678 or gteixeira@uidaho.edu)
More information: https://go.uidaho.edu/fresh-pack-potato-symposium
2026 Miller Research Potato Pest Management Field Day - August 20
All Crops All Locations
Posted on: August 4, 2026 by Jeff Miller
<p>The 2026 Miller Research Potato Pest Management field day will be Thursday, August 20 from 9:00 am to 12:00 pm. Cost is $20. Three ISDA pesticide recertification credits and three CCA PM credits have been awarded for the meeting. Lunch will be provided. More information can be found at the website and in the attached flier.</p>
» https://millerresearch.com/event/2026-miller-research-potato-pest-management-field-day/
