Released May 10, 2024

The Prairie Pest Monitoring Network is back for the 2024 growing season! Wishing everyone smooth and safe seeding!

Catch Monday’s Insect of the Week for Week 1- What’s eating my crop? Cutworm damage

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Weather synopsis

Due to technical difficulties (typical as the season begins), a full weather summary is unavailable this week.

The 2023 growing season was warmer than normal across the southern prairie region in 2023 (Fig. 1), with the observed prairie average growing season temperature coming in at 16.5°C. This was 2.6°C warmer than the 30-year average of 13.9°C.

Figure 1. Growing season average temperature (°C) observed across the Canadian prairies for the period of May 1 to August 31, 2023.

The 2023 growing season was also characterized by wet conditions in northern Alberta and parts of northern and eastern Saskatchewan but very dry conditions in the southern prairie region, especially in southern Alberta (Fig. 2). Conditions remained fairly dry through September, October, November and December of 2023 with below average snowfall accumulation across most of the prairies. The first significant snowfall of the winter season in Saskatoon, for example, did not occur until early January. Despite some significant snowfall events between January 01 and March 31, 2024, the Canadian Drought Monitor indicated that the majority of the prairie region was abnormally dry or experiencing moderate to exceptional drought conditions (

Large swaths of the prairies received significant rain over the last week and temperatures have been cool/mild since April 1. Spring 2024 conditions, at least so far, have been quite different from spring conditions in 2023.

Growing degree day (GDD) maps for Base 5 ºC and Base 10 ºC (April 1-May 8, 2024) can be viewed by clicking the hyperlinks. Over the past 7 days (May 2-8, 2024), the lowest temperatures recorded across the Canadian prairies ranged from < -12 to > 2 °C while the highest temperatures observed ranged from <7 to >21 °C. 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.

Review 2023 insect pest monitoring maps

The Prairie Pest Monitoring Network is a collaborative effort. In-field monitoring data is collected at regional, provincial, and prairie-wide levels. Using Geographic Information Software (GIS), surface area maps are generated from survey data to create prairie-wide maps. Techniques are used to smooth transitions between zones and can affect the values in localized areas and, as such, these maps should be interpreted on a regional level only.

Annual insect distribution maps are posted by the PPMN and can be reviewed on this webpage.

TIP: To prepare for the 2024 field scouting season, review the 2023 Prairie-wide Maps. Take a moment to note which geographic regions for each corresponding insect pest is highlighted in yellow, orange or red – these areas are worth prioritizing for 2024’s field scouting efforts.


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.

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.

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 week of monitoring includes:

  • Alberta – So far, Shelley Barkley (Alberta Agriculture and Irrigation) reported that low numbers of diamondback moth were captured at a few monitoring locations in southern and eastern Alberta and noted the Alberta Agriculture and Irrigation’s ‘live’ reporting map is active for 2024.
  • Saskatchewan – Dr. James Tansey (Saskatchewan Ministry of Agriculture) also reported that adult diamondback moth were captured at a few locations in Saskatchewan.
  • Manitoba – Dr. John Gavloski (Manitoba Agriculture) reported that diamondback moth were observed from 13 traps; 3 traps intercepted 10 or above, but no larger counts yet.
Figure 1. The life stages of the diamondback moth (Plutella xylostella), which can have multiple generations per year. Photos: AAFC-Saskatoon-J. Williams.

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.


Grasshopper populations have been building over the past few years, as warm and dry conditions, especially in the southern prairies have been very favourable for grasshopper development. In 2023, grasshopper development got off to a quick start in April and May due to warmer than normal temperatures and dry conditions. Adult pest grasshoppers were collected at field sites across the prairies as early as June 15, which is the earliest in recent memory. Grasshopper densities were very high in many areas of the prairies by late summer in 2023 (Fig. 1) and conditions were optimal for egg laying and for embryonic development in the late summer and early fall.

Figure 1. Adult grasshopper densities observed late in the summer of 2023.

Although spring 2024 has been cooler and wetter than spring 2023, the grasshopper risk in 2024 could still be very high, especially in southern Alberta and southern Saskatchewan. All production regions of the Canadian prairies should prioritize grasshopper field scouting in the spring of 2024.

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.
● 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 Forestry, 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 prairies.

Pea leaf weevil

In the spring, overwintered adults disperse to feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas). This feeding can produce a characteristic, scalloped (or notched) edge (Fig. 1).  Females lay their eggs in the soil either near or on developing pea or faba bean plants from May to June.

Figure 1. Examples of adult pea leaf weevil damage on field pea seedlings, (A) seedling with notches on all nodes, (B) stereotypical crescent-shaped notches on the leaf margin, (C) clam or terminal leaf of the pea seedling with arrows indicating the feeding notches.
All photos courtesy of Dr. L. Dosdall.

The annual pea leaf weevil survey is conducted from late May to early June. Results from the 2023 annual survey are shown in Fig. 2. 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. Dr. Meghan Vankosky (AAFC-Saskatoon) and Dr. Boyd Mori (University of Alberta) are also looking for field sites to collect adult pea leaf weevils for laboratory experiments this spring. For these experiments, we can collect adult weevils from field pea or faba bean fields and weevils will be collected by hand from plants in the field or with a sweep net in field margins. Please contact Meghan to volunteer field sites for adult weevil collection (

Figure 2. Results of the 2023 annual pea leaf weevil survey conducted in the spring of 2023.

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.

Alfalfa weevil

The alfalfa weevil, Hypera postica, overwinters as an adult that typically flies to alfalfa fields in April and May. Adult females start to lay eggs in May. Adults consume alfalfa foliage, but typically do not cause economic levels of damage. However, larval feeding peaks in June and, if high densities are present, can cause yield losses. Thus, field scouting to assess larval stages and densities should begin in May through to June. Review the alfalfa weevil life cycle and the damage it causes.

Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from 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.

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 will start soon! Bookmark the Crop Pest Update Index to prepare for the season and also bookmark the insect pest homepage to access fact sheets and more!

SASKATCHEWAN’S Crop Production News is coming soon. Bookmark their insect pest homepage to access important information! Access and review the Crops Blog Posts with help for 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.
Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.
Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map.

Crop report links

Access the latest provincial crop reports produced by:
Manitoba Agriculture (subscribe to receive OR access a PDF copy of the May 7, 2024 report or the April 30, 2024 report).
Saskatchewan Agriculture (or access a PDF copy of the April 30-May 6, 2024 report).
Alberta Agriculture and Irrigation (no PDF copy available yet for 2024).

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 6, 2024 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the May 7, 2024 edition).