Tag: Ceutorhynchus obstrictus

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Manitoba, Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2025Jun19 but will be updated with 2025 reports as the season progresses).

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Manitoba, Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2025Jun19 but will be updated with 2025 reports as the season progresses).

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Manitoba, Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2025Jun19 but will be updated with 2025 reports as the season progresses).

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2022Jul28 but will be updated with 2025 reports as season progresses).

This image has an empty alt attribute; its file name is 2022Jul28_CSPW-map_AB.png

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2022Jul28 but will be updated with 2025 reports as season progresses).

This image has an empty alt attribute; its file name is 2022Jul28_CSPW-map_AB.png

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (Fig. 1; left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (Fig. 1; right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Figure 1. Cabbage seedpod weevil (left) and egg dissected from within a canola pod (right). Photos: the late Dr. Lloyd Dosdall.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (Fig. 1; right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically, a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (Fig. 2; left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod (Fig. 2; right photo, lower pod), feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole (Fig. 2; right photo, upper pod) from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Figure 2. Larva feeding amongst developing seeds within canola pod (left) and larval entrance hole (right photo, lower pod) compared to mature larval exit hole (right photo, uppower pod). Photos: the late Dr. Lloyd Dosdall.

Prairie-Wide Monitoring: The annual cabbage seedpod weevil survey is performed in canola at early flower stages using sweep-net collections. Review the prairie-wide historical survey maps for this insect species. Review the PPMN monitoring protocol although the provinces of Alberta, Saskatchewan, and Manitoba have specific survey protocols for their respective network cooperators. Commercial fields where comparatively higher densities of adult cabbage seedpod weevils were observed in 2024 are highlighted yellow, orange, or red in the geospatial map featured in Figure 3. Areas where historically higher densities of cabbage seedpod weevil were observed in 2024 are worth prioritizing in 2025.

Figure 3. Densities of cabbage seedpod weevil (Ceutorhynchus obstrictus) observed in sweep-net samples retrieved from commercial fields of canola (Brassica napus) grown in Saskatchewan, Alberta, and the British Columbia portion of the Peace River region in 2024.

In-Field Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report field observations and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2022Jul28 but will be updated with 2025 reports as season progresses).

This image has an empty alt attribute; its file name is 2022Jul28_CSPW-map_AB.png

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jul04).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below for reference; retrieved 2024Jun27).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Ministry of Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Cabbage seedpod weevil

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Irrigation (screenshot provided below as an example; retrieved 2022Jul28).

This image has an empty alt attribute; its file name is 2022Jul28_CSPW-map_AB.png

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Irrigation, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Cabbage seedpod weevil monitoring

There is one generation of cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) per year. The overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved 2022Jul28).

CSPW was the Insect of the Week for Wk08 in 2021!

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil 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. The Canola Council of Canada’s “Canola Encyclopedia” also summarizes CSPW.

Cabbage seedpod weevil monitoring

Monitoring is already underway for cabbage seedpod weevil (CSPW; Ceutorhynchus obstrictus) in southern areas of the prairies – it was the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintered adult is an ash-grey weevil measuring 3-4mm long (e.g., lower left photo).  Mating and oviposition are quickly followed by eggs hatching within developing canola pods (e.g., lower right photo). The highly concealed larvae feed within the pod, consuming the developing seeds.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.

Cabbage seedpod weevil monitoring

Monitoring is already underway for cabbage seedpod weevil (Ceutorhynchus obstrictus; CSPW) in southern areas of the prairies – it’s the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo).  Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.

Monitoring:

  • Begin sampling when the crop first enters the bud stage and continue through the flowering. 
  • Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.  
  • Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.  
  • Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.  
  • An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). 
  • Consider making insecticide applications late in the day to reduce the impact on pollinators.  Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.  
  • High numbers of adults in the fall may indicate the potential for economic infestations the following spring.

Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss.  Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo).  Eggs are oval and an opaque white, each measuring ~1mm long.  Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.

There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo).  The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds.  A single larva consumes about 5 canola seeds.  The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell.  Approximately 10 days later, the new adult emerges to feed on maturing canola pods.  Later in the season, these new adults migrate to overwintering sites beyond the field.

Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).

Please find additional detailed information for CSPW in fact sheets posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or the Prairie Pest Monitoring Network.  Also refer to the cabbage seedpod weevil pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.