Released May 24, 2024

Welcome to Week 3 for the 2024 growing season!  Field scouting starts to ramp up with a few more insects to add to the “watch” list. This week includes:
• Weather synopsis (abridged)
• Cutworms
• Flea beetles
• Grasshoppers
• Diamondback moth
• Pea leaf weevil
• Tick tips
• Crop production guide links
• Provincial insect pest report links
• Crop report links
• Previous posts

Catch Monday’s Insect of the Week for Week 3 – What’s eating my crop? Wireworms

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Weather synopsis

A full weather summary is unavailable this week.

Growing degree day (GDD) maps for the Canadian prairies for Base 5 ºC and Base 10 ºC (April 1-May 13 2024) can be viewed by clicking the hyperlinks. Over the past 7 days (May 16-22, 2024), the lowest temperatures recorded across the Canadian prairies ranged from < -6 to > 6 °C while the highest temperatures observed ranged from < 6 to >24 °C. In terms of precipitation across the Canadian prairies, review the growing season accumulated precipitation (April 1-May 22, 2024), the growing season percent of average precipitation (April 1-May 22, 2024), and the past 7 days (as of May 22, 2024). Access these maps and more using the AAFC Maps of Historic Agroclimate Conditions interface.

Growers can bookmark the AAFC Maps of Current Agroclimate Conditions for the growing season. Historical weather data can be accessed at the AAFC Drought Watch Historical website, Environment and Climate Change Canada’s Historical Data website, or your provincial weather network. The AAFC Canadian Drought Monitor also provides geospatial maps updated monthly.


Reminder – Cutworm scouting spans April to late June across the Canadian prairies!

Scout fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look.  Plan to follow up by walking these areas either very early or late in the day when some cutworm species (or climbing cutworms) move above-ground to feed.  Start to dig below the soil surface (1-5 cm deep) near the base of symptomatic plants and also any healthy plants immediately adjacent to missing rows or wilting or clipped plants.  Some cutworms feed by remaining just below the soil surface, clipping then pulling the plant below as they munch away! If the plant is well-established (e.g., perennial grass or legume), check within the crown plus in the adjacent soil.  The culprits could be cutworms, wireworms, or more!

Important: Several species of cutworms (Lepidoptera: Noctuidae) can be present in fields.  They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning.  A field guide is available to help growers scout and manage the various species of cutworms that can appear in field crops grown on the Canadian prairies.  Cutworm Pest of Crops is available free in either English or French! Download a searchable PDF copy to access helpful diagnostic photos plus a table showing which larvae are active at different points in the growing season!

Other vital resources to scout and manage cutworms include:
● For anyone on the Canadian prairies, Manitoba Agriculture’s Cutworms in Field Crops fact sheet includes action and economic thresholds for cutworms in several crops, important biological information, and great cutworm photos to support in-field scouting.
● For Albertans….. If you find cutworms, please consider using the Alberta Insect Pest Monitoring Network’s “2024 Cutworm Reporting Tool” then view the live 2024 cutworm map updated daily. Review the live map to see where cutworms are appearing then prioritize in-field scouting accordingly.
● Cutworms were featured as 2024’s first Insect of the Week.

Flea beetles

Two species, the striped and crucifer flea beetles, are the most chronic and economically important insect pests of cruciferous field crops grown across western Canada. Both species are already active so prioritize field scouting in fields of emerging and seedling canola and mustard. All cruciferous crops and plants of any Brassicaceae are similarly attractive and can suffer damage from crucifer (P. cruciferae) and striped flea beetles (P. striolata).

Damage to emerging crops can progress very quickly when flea beetle densities are high, even within the same day! The cotyledon stage of canola is most vulnerable to flea beetle feeding.

Learn more about flea beetle damage in canola by reviewing the Insect of the Week (Wk 2 released May 13, 2024). Review photos of flea beetle feeding damage posted in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent feeding damage and to apply the action threshold of 25 % leaf area of cotyledons. The Canola Council of Canada’s Canola Encyclopedia also features flea beetles along with an excellent visual guide to help estimate feeding damage.

Access biological and pest management information posted by Saskatchewan Agriculture, Manitoba Agriculture, or the Canola Council of Canada’s Canola Encyclopedia. Refer to the flea beetle page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.


Conditions in spring 2024 continue to be cooler and wetter than observed in spring 2023. These cool, wet conditions could be slowing down the development of grasshopper eggs and grasshopper nymphs. Many factors will influence grasshopper populations over the next few weeks. Because grasshoppers had so much time to lay eggs in summer and fall of 2023, and because the eggs had more time to develop before overwintering, grasshopper risk remains quite high in spring of 2024.

Grasshopper nymphs have already been observed at multiple locations in southern Alberta and southern Saskatchewan. Areas across the Canadian prairies now need to be scouted as the grasshopper hatch continues over the coming weeks. Scout to assess both densities AND development stage of the nymphs. Tip – younger or earlier instar nymphs are easier to manage but visit sites every few days to stay on top of local field conditions.

Important – A preliminary summary of available thresholds for grasshoppers has been kindly shared by Dr. J. Tansey (Saskatchewan Agriculture) in Table 1. When scouting, compare in-field counts to the available threshold value for the appropriate host crop AND for field or ditch situation. Available thresholds (nominal and economic) help support producers while protecting beneficials (i.e., predators, parasitoids, and pathogens) that regulate natural populations of grasshoppers.

More Grasshopper Scouting Tips:
Review grasshopper diversity and photos of nymphs, adults, and non-grasshopper species to aid in-field scouting from egg hatch and onwards.
● Prioritize any area where grasshopper densities were high in 2023!
● Carefully check roadside ditches and along field edges but also check the edge of the crop and into the actual field.
● A sweep-net can ‘detect’ grasshopper nymphs, however, economic thresholds for grasshoppers are based on the number of grasshoppers per square-metre counts.
● Access the PPMN’s Grasshopper Monitoring Protocol as a guide to help implement in-field monitoring.
● Review grasshopper lifecycle, damage and scouting and economic thresholds to support sound management decisions enabling the preservation of beneficial arthropods and mitigation of economic losses.

Biological and monitoring information (including tips for scouting and economic thresholds) related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan AgricultureAlberta Agriculture and Irrigation, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our Field Guides page. Review the historical grasshopper maps based on late-summer in-field counts of adults performed across the Canadian prairies.

Diamondback moth

Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.

Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.

Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Thank you to the many people who deployed and are weekly checking traps across the BC Peace, Alberta, Saskatchewan, and Manitoba! Weekly trap interceptions are observed to generate cumulative counts.

As the season progresses, cumulative count estimates arising from these pheromone traps are broadly categorized to help producers prioritize and time in-field scouting for larvae. Preliminary data from the initial weeks of monitoring includes:

  • Alberta – So far, two traps in southern Alberta have caught more than 10 moths, one in Mountain View County and one in Kneehill County. Visit Alberta Agriculture and Irrigation’s ‘live’ reporting map for updates through the 2024 growing season.
  • Saskatchewan – Dr. James Tansey and Carter Peru (Saskatchewan Ministry of Agriculture) shared that traps near Regina (RM129), Makwa (RM561), and Lumsden (RM189) have caught 20-25 adult diamondback moths. Several traps have also caught more than 25 moths so far this monitoring season, including traps near Laura (RM315), Delisle (RM345), Macroie (RM285), and Buchanan (RM304).
  • Manitoba – Dr. John Gavloski (Manitoba Agriculture) reported that five diamondback moth traps have now captured more than 25 moths in Manitoba. These traps are located in the Central region (2), Eastern region (1) and North Interlake region (2) of the province. So far, the highest cumulative count in a single trap is 69.

Biological and monitoring information for DBM (including tips for scouting and economic thresholds) is posted by Manitoba AgricultureSaskatchewan Agriculture, and the Prairie Pest Monitoring Network.  Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.

Pea leaf weevil

The annual pea leaf weevil survey will start later in May or in early June. If you are planting field peas this year, please consider volunteering your fields for this survey. The survey is conducted by counting the characteristic ‘u’ shaped feeding notches made by adult pea leaf weevil at several locations along the field edge.

Adult pea leaf weevil are needed for experiments this spring! Please contact Dr. Meghan Vankosky (AAFC-Saskatoon; if you are planting peas or faba beans and would give us permission to hand-collect adult weevils from your fields. Thank you!

Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol. Also access the Pea leaf weevil page re and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture, and the Prairie Pest Monitoring Network.  Also refer to the pea leaf weevil page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our Field Guides page.

Tick Tips

When scouting, avoid unwanted passengers – remember to watch for ticks at this time of year!  Blacklegged (deer) ticks can carry Lyme Disease, anaplasmosis, babesiosis, or Powassan virus.  Access information on how to safely remove and identify a tick made available by Health Canada which also recommends these “before you go” ways to help prevent tick bites:
• light coloured, long-sleeved shirts and pants help you spot ticks easier.
• tuck shirt bottoms into pants and pant cuffs into socks – seal yourself in and ticks out!
• closed-toe shoes keep ticks out!
• apply an insect repellent containing DEET or Icaridin to clothing and exposed skin (according to product label directions).
• wear permethrin-treated clothing (according to product label direction).
…. and review the full set of helpful tips!

Continued surveillance is important and enables tracking of Lyme disease incidence and risk. Follow the links to learn more and to submit ticks if you live in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, or Quebec. Access additional information posted by Health Canada related to Lyme disease surveillance which also summarized that, between 2009 and 2023, 19,983 human cases of Lyme disease were reported to provincial public health units across Canada.

Another option is the free eTick APP, a public platform for image-based identification and population monitoring of ticks in Canada. Both Google Play and iOS versions of the App enable users to upload tick photos for help with identification.

Public Health Agency of Canada has a Top 10 Tick Hiding Spots on Your Body available as a poster in multiple languages including Mi’kmaq, Mohawk, Ojibwe (Eastern), French, English, Spanish, Tagalog, Arabic, Punjabi, Chinese (simplified and traditional), and Italien. An example in English is posted below for your quick reference (Fig. 1) so check it, then yourself, and your pets!

Figure 1. Screenshot of Public Health Agency of Canada’s infographic of top 10 tick hiding spots on your body (2020; retrieved 2024May23).

Crop production guide links

Reminder – Crop Production Guides are posted to websites for Alberta, Saskatchewan, and Manitoba for 2024!

Every year, these guides are updated with product information and so much more! Hard copies can be purchased via the above websites but also look for the download button to access FREE downloadable PDF copies!

A few other helpful tools to keep at your finger tips:

The Canadian Grain Commission has information to help you manage stored grain.  Read tips to prepare your bins to prevent insect infestations.  If there are insects in your grain, use their online diagnostic tools to help identify the problem species.  If pest species are confirmed, there are control options – read more to make the right choice for your grain storage system and your specific grain.

Provincial insect pest report links

Prairie-wide provincial entomologists provide insect pest updates throughout the growing season. Follow the hyperlinks to readily access their information as the growing season progresses:

MANITOBA’S Crop Pest Updates for 2024 have started! Access the online May 23, 2024 report (or review a PDF copy). Bookmark the insect pest homepage to access fact sheets and more!
Diamondback moth pheromone trap monitoring in MB – Dr. John Gavloski (Manitoba Agriculture) reported that, “Diamondback moth have been found in 55 out of 68 traps that counts were reported from. Trap counts have generally been low so far, however, some moderate counts have occurred in the Eastern, Interlake and Central regions. The highest cumulative trap count so far is 69 from a trap near Riverton in the Interlake region.”
True armyworm in MB – Dr. John Gavloski (Manitoba Agriculture) reported that, “A network of pheromone-baited traps are being monitored at 34 locations from early-May until late-July to determine how early and in what levels populations of armyworms have arrive. Some moderate counts have occurred from traps in the Eastern and Interlake regions of Manitoba. The highest cumulative count is 76, from a trap near Riverton in the Interlake region.”
Beneficial insect monitoring in MB – “Weekly monitoring of the levels and stages of five groups of
predaceous insects; lady beetles, green lacewings, hover flies, minute pirate bugs and damsel bugs”, will be undertaken using sweep-net sampling.

SASKATCHEWAN’S Crop Production News is back for the 2024 growing season! Access the online Issue #1 report. Bookmark their insect pest homepage to access important information!
Grasshopper hatch in SK – Updates that, ” eggs are being found by agrologists”, that “recent rains are unlikely to have a major impact on grasshopper populations”, that “nymphs have been found near OUtlook, Kindersley, and Regina”, and emphasizes the importance of “producers start(ing) to scout for eggs or nymphs”.
Flea beetle monitoring in SK – Updates that, “fields in northern Saskatchewan have heavy flea beetle feeding on volunteer canola” and recommends, “producers across the province should frequently scout canola and mustard” following seedling emergence.
• Also access the Crops Blog Posts that announced registration for the Crop Diagnostic School 2024 but also posts help for scouting fields for wireworms (May 2024), grasshopper identification: pest or not (Apr 2024), a summary of wheat midge populations and management (Mar 2024), and a description of pea leaf weevil populations (Feb 2024).

ALBERTA’S Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. Remember, AAF’s Agri-News occasionally includes insect-related information, e.g., flea beetle control (May 6, 2024); cereal insect pests, latest on insects in canola, and post-emergence wireworm scouting (May 13, 2024).
Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, cumulative trap counts from the 29 reporting sites reflect low or “no risk” (as of May 23, 2024).
Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 7 surveyed sites have reported from across the province and all are in southern Alberta.

Crop report links

Access the latest provincial crop reports produced by:
Manitoba Agriculture (subscribe to receive OR access a PDF copy of the May 21, 2024 report).
Saskatchewan Agriculture (or access a PDF copy of the May 14-20, 2024 report).
Alberta Agriculture and Irrigation (or access a PDF copy of the May 7, 2024 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the May 20, 2024 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the May 21, 2024 edition).

Previous posts

As the growing season progresses, the Weekly Update topics move on and off the priority list for in-field scouting. Even so, it is still useful to keep them at hand to support season-long monitoring. Click to review these earlier 2024 Posts (organized alphabetically):
2023 Risk maps
Alfalfa weevil (Wk 02)
Scouting charts – canola and flax (Wk 03 of 2022)
Wind trajectory summaries unavailable (Wk 01)