Released June 14, 2024

Welcome to Week 6 for the 2024 growing season!  This week includes:
• Weather synopsis
• Grasshoppers
• Diamondback moth
• Bertha armyworm
• Cereal leaf beetle
• Detecting and reporting invasive insects
• Welcome Prairie Weed Monitoring Network
• Provincial insect pest report links
• Crop report links
• Previous posts

Catch Monday’s Insect of the Week for Week 6 – What’s eating my crop? Grasshoppers

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Weather synopsis

This week’s weather summary was kindly provided by the Prairie Crop Disease Monitoring Network (PCDMN).

This past week, cooler temperatures were observed across most of the prairies. Growing season temperatures have been lower than average while rainfall amounts continue to be above average. This past week (June 3-9, 2024) temperatures were 1.2 °C below climate normal values. The average temperature across the prairies was 12.5 °C (Figure 1). Warmest temperatures were observed across a large area that extended west of Winnipeg to Saskatoon and Lethbridge. Seven day cumulative rainfalls were highly variable (Figure 2). Average cumulative seven day rainfall was 16.3 mm. Lowest rainfall values were observed across southern and western regions of the prairies, while the Parkland region had higher rainfall amounts.

Figure 1. Seven day average temperature (°C) observed across the Canadian prairies for the period of June 3-9, 2024.
Figure 2. Seven day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 3-9, 2024.

The average 30 day temperature (May 11 – June 9, 2024) was 11.4 °C and was 0.5 °C cooler than the long term average temperature. Warmest temperatures were observed south of an area extending from Winnipeg to Saskatoon and southwest to Lethbridge (Figure 3). Most of the prairies have reported 30 day rainfall amounts were normal to above normal. Average cumulative rainfall (mm) over the past 30 days was 65 mm and was 152% of climate normal values. The Peace River region continues to report lowest rainfall totals (Figure 4). Cumulative rainfall continues to be greatest across most of Manitoba.

Figure 3. 30 day average temperature (°C) observed across the Canadian prairies for the period of May 11 – June 9, 2024.
Figure 4. 30 day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 11– June 9, 2024.

Since April 1, the 2024 growing season has been 0.6 °C warmer than average. Warmest average temperatures were observed across the southern prairies (Figure 5). Growing season rainfall has been above normal across most of the prairies. Rain amounts have been 184% of climate normals (Figure 6). Highest cumulative rainfall has been greatest for most of Manitoba and southern Alberta (Figure 7).

Figure 5. Growing season average temperature difference from climate normal (°C) observed across the Canadian prairies for the period of April 1 – June 9, 2024.
Figure 6. Growing season percent of normal rain (%) observed across the Canadian prairies from April 1 to June 9, 2024.
Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 – June 9, 2024.

Growing degree day (GDD) maps for the Canadian prairies for Base 5 ºC and Base 10 ºC (April 1-June 10 2024) can be viewed by clicking the hyperlinks. Over the past 7 days (to June 12, 2024), the lowest temperatures recorded across the Canadian prairies ranged from < -4 to > 7 °C while the highest temperatures observed ranged from < 3 to >25 °C. In terms of precipitation across the Canadian prairies, review the growing season accumulated precipitation (April 1-June 12, 2024), the growing season percent of average precipitation (April 1-June 12, 2024), and the past 7 days (as of June 12, 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.


Nymphs of economically important grasshopper species have been observed at multiple locations in southern Alberta and southern Saskatchewan since mid-May. On Jun 6, few grasshopper nymphs were active at sentinel sites between Saskatoon and Rosetosn SK, likely due to cool, wet, and windy conditions.

Scout for grasshoppers to keep informed of their developmental stage and population density.

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.
● It is best to scout on warm days when grasshopper nymphs are more active and easier to observe.
● Carefully check roadside ditches and along field edges but also check the edge of the crop and into the actual field.
● Younger or earlier instar nymphs are easier to manage – visit sites every few days to stay on top of local field conditions.
● 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.

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 situations. Available thresholds (nominal and economic) help support producers while protecting beneficials (i.e., predators, parasitoids, and pathogens) that regulate natural populations of grasshoppers.

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.

The week of May 27, 2024, very mature larvae were retrieved in flixweed in southern Alberta (Barkley, pers.comm. 2024). Thus, a second generation of adult diamondback moth is likely active in southern parts of the prairies.

Pheromone-baited Delta traps housing sticky cards are used to monitor diamondback moth across the Canadian prairies. Research has shown that cumulative counts > 25 moths indicate elevated risk. In those areas, it then becomes important to scout and assess larval densities.

Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.

Provincial entomologist (Barkley, Tansey, Peru, Gavloski) have kindly provided the following summary for this week:
• Alberta – two traps have caught > 25 adult diamondback moths; one trap deployed in the County of Warner (as of June 15, 2024) and one trap deployed in the County of Grande Prairie (as of June 8, 2024).
• Saskatchewan – 6 RMs have observed cumulative counts >25 (as of June 6, 2024); traps are located near Regina (RM 129), Macroie (RM 285), Buchanan (RM 304), Laura (RM 315), Delisle (RM 345) and Makwa (RM 428). As of June 6, 2024, the highest cumulative count was 61 moths.
• Manitoba – pheromone traps at 20 locations have captured > 25 moths, with cumulative trap catches ranging form 28 to 187. All of the traps with elevated risk are located in the Central, Eastern, South Interlake and North Interlake regions of Manitoba.  

Scouting and pest management for diamondback moth depends on in-field counts of larvae per metre2! This means plants need to be pulled and tapped off to assess the number of larvae! Use Figure 1 below to help identify the different stages of diamondback moth.

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.

Bertha armyworm

Pheromone traps used to monitor bertha armyworm are typically set up along canola fields when pupal development reaches 75-80%; the 2024 monitoring season started the week of June 10, 2024.

Use the images below (Fig. 1) to help identify moths from the by-catch that will be retained in the green phermone-baited unitraps.

Figure 1. Stages of bertha armyworm from egg (A), larva (B), pupa (C), to adult (D). Photos: J. Williams (Agriculture and Agri-Food Canada).

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting or review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm! 

Please refer to this week’s Provincial Insect Pest Report Links to find the most up-to-date information summarizing weekly cumulative counts compiled by provincial pheromone trapping networks across the Canadian prairies in 2024.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm 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.

Cereal leaf beetle

The cereal leaf beetle (Chrysomelidae: Oulema melanopus) has a broad host range. Wheat is the preferred host, but adults and larvae also feed on leaf tissue of oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Yield quality and quantity is decreased, if the flag leaf is stripped. Fun fact: Cereal leaf beetle larvae carry their own fecal waste above their body to help protect themselves from predators.

Fortunately, the parasitoid wasp, Tetrastichus julis Walker (Hymenoptera: Eulophidae), is an important natural enemy of cereal leaf beetle larvae. Learn more about this beneficial insect species featured in Week 9 of 2023’s Insect of the Week!

Cereal Leaf Beetle Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  

Figure 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the midvein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Access scouting tips for cereal leaf beetle or find more detailed information by accessing the Oulema melanopus page 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.

Detecting and reporting invasive insects

Reminder Early detection is critical for slowing the spread of invasive insects.

A collaborative project developed by the Insect Surveillance Community of Practice and Canadian Plant Health Council has led to a series of posters featuring invasive insects of concern. Each poster includes a QR Code that users can scan to report observations of these priority invasive and migratory insects. Posters are free, printable PDF copies and highlight species of concern across Canada’s regions:
• Prairies (English or French)
• British Columbia (English or French)
• Ontario & Quebec (English or French)
• Atlantic (English or French)

The English version of the Prairies poster is below to view (Front and Back) Use the QR code to report detections or observations of these invasive species.

Welcome Prairie Weed Monitoring Network

Reminder – Last week, the Prairie Pest Monitoring Network is excited to promote the official launch of the Prairie Weed Monitoring Network’s official website,!

The Western Grains Research Foundation (WGRF) is excited to announce the official launch of, a comprehensive online platform designed to support the Prairie Weed Monitoring Network (PWMN) through the Integrated Crop Agronomy Cluster.

Led by Dr. Charles Geddes and Julia Leeson from Agriculture and Agri-Food Canada (AAFC), the PWMN is a pioneering initiative aimed at implementing an all-inclusive weed biovigilance strategy across the Canadian prairies. The PWMN is a coordinated collaboration among federal, provincial, and academic weed science experts.

 “The launch of marks a significant milestone in the development of the PWMN,” says Dr. Charles Geddes, Weed Scientist, AAFC. “ will serve as the digital home of the PWMN, offering a wealth of resources and up-to-date information on weed abundance, herbicide resistance, and integrated weed management specific to the Canadian prairies.

The PWMN will build on the existing and highly successful models of the Prairie Pest Monitoring Network, and Prairie Crop Disease Monitoring Network, and will formalize and coordinate weed awareness, detection/identification, and assessment activities for the Prairie region.

Laura Reiter, WGRF Board Chair, expressed enthusiasm for the project, stating, “ will be a great resource for farmers, agronomists, and researchers. The website is a great opportunity to provide the agricultural industry with the information required to manage weeds effectively, anticipate new threats, and mitigate herbicide-resistant weeds.”

The Prairie Weed Monitoring Network (PWMN) is supported by funding from Agriculture and Agri-Food Canada through the Sustainable Canadian Agricultural Partnership’s AgriScience Program – Clusters Component, WGRF, Alberta Grains, Alberta Canola, SaskCanola, Saskatchewan Wheat Development Commission, Saskatchewan Pulse Growers, Manitoba Crop Alliance, Manitoba Pulse and Soybean Growers, Manitoba Canola Growers Association, and Prairie Oat Growers Association.

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 June 13, 2024 report (or PDF copy). Bookmark the insect pest homepage to access fact sheets and more! Highlights pulled from the latest report include:
Flea beetles in MB – Dr. J. Gavloski reported that, “flea beetels have been a concern in some fields resulting in some foliar insecticide applications and reseeding. Spraying for flea beetles this week was reported from the Northwest, Central and Eastern regions. In the Northwest region there are reports of some canola fields having been sprayed twice for flea beetles, and one field having been sprayed three times for flea beetles. Some reseeding of canola was reported from the Northwest region, and a couple of fields near Portage la Prairie in the Central region were reseeded because of flea beetle damage.”
Cutworms in MB – “Cutworms have been causing damage in several crops. Insecticide applications for cutworms over the past week have occurred in canola, sunflowers, peas, and flax, with most of these reports coming from the Southwest or Central regions. Some canola and a small area of corn in the Southwest region were reseeded because of cutworms.”
• “Wireworm damage to corn was noted in a field in the Central region.”
• “Seedcorn maggots have been reported in sunflowers, but no serious damage.”
Diamondback moth pheromone trap monitoring in MB – Reports that diamondback moth were present “in 73 out of 89 traps” and that, “trap counts have generally been low so far in the Northwest and Southwest regions” but “some moderate counts have occurred in the Eastern, Interlake and Central regions. The highest cumulative trap count so far is 187 from a trap near Riverton in the Interlake region.”
True armyworm in MB – “Counts have been low so far in the western regions of Manitoba, with some moderate counts in the Central region” while “some higher counts occurred in some traps in the Eastern and Interlake regions”. “The highest cumulative count is 360, from a trap near Dencross in the Eastern region. There are some areas in the Central, Eastern and Interlake regions where

Dr. John Gavloski (Manitoba Agriculture) reported that, “”Some moderate to high counts have occurred from traps in the Eastern and Interlake regions of Manitoba. The highest cumulative count is 222, from a trap near Dencross in the Eastern region” and “(it) would be good to prioritize looking for armyworm larvae while scouting cereals and forage grasses” in “some areas of the Central, Eastern and Interlake regions”.

SASKATCHEWAN’S Crop Production News is back for the 2024 growing season! Access the online Issue #2 report. Bookmark their insect pest homepage to access important information!
As crops emerge in SK – “Be on the lookout for early season pests such as cutworms, wireworms, flea beetles, and root rots”.
Grasshopper hatch in SK – Stay “aware of early season grasshopper damage” as “there are reports of nymphs damaging seedlings” in crops. Access the report to link to information on nymph damage and economic thresholds. The report includes articles on “How to Scout for Grasshoppers” plus “Grasshopper’s Natural Enemies
Diamondback moth in SK Preliminary cumulative count data from pheromone traps across the province can now be reviewed online.
• 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., how to manage stem feeding from flea beetles, keep canola bins malathion-free, scout for grasshoppers and other pests (June 10, 2024); scout for insect pests (June 3, 2024), scout for grasshoppers (May 27, 2024), 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 have been recorded from 31 reporting sites and 28 remain in the “no risk” category as of June 13, 2024). Three sites report “elevated risk” (as of June 13, 2024); they occur within the County of Grande Prairie, County of Warner, and Vulcan County.
Cutworm live monitoring map for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. So far, 10 surveyed sites have reported from across the province, nine falling within southern Alberta and one report from the County of Grande Prairie.

Crop report links

Access the latest provincial crop reports produced by:
Manitoba Agriculture (subscribe to receive OR access a PDF copy of the June 11, 2024 report).
Saskatchewan Agriculture (or access a PDF copy of the June 4-10, 2024 report).
Alberta Agriculture and Irrigation (or access a PDF copy of the June 4, 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 June 10, 2024 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the June 11, 2024 edition).

Previous posts

As the growing season progresses, the Weekly Update topics move on and off the priority list for in-field scouting. It remains useful to keep the list at hand to support season-long monitoring. Click to review these earlier 2024 Posts (organized alphabetically):
2023 Risk maps
Alfalfa weevil (Wk 02)
Crop production guide links (Wk 03)
Cutworms (Wk 05)
Field heroes (Wk 05)
Flea beetles (Wk 04)
Pea leaf weevil (Wk 05)
Scouting charts – canola and flax (Wk 03 of 2022)
Tick tips (Wk 04)
Wind trajectory summaries unavailable (Wk 01)