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Order: Coleoptera
Family: Attelabidae<\/p>\n
Adults of sunflower headclipping weevil (Haplorhynchites aeneus<\/em>) are shiny, black, and slightly hairy and measure about 8.5 mm (1\/3 inch) in length from the abdominal rear to the tip of the snout. Like all weevil species, the snout-like protrusion of adults extends from their head and contains antennae and mouthparts. Larvae of the sunflower headclipping weevil measure 4-6 mm (~1\/4 inch) long, are yellow or cream colored, C-shaped, and have a brown head capsule.<\/p>\n [\/et_pb_text][et_pb_blurb title=”Quick Facts” use_icon=”on” font_icon=”||fa||900″ icon_color=”#F15625″ image_icon_width=”36px” _builder_version=”4.24.2″ _module_preset=”default” header_level=”h3″ header_font=”|||on|||||” header_text_align=”center” header_font_size=”26px” background_color=”#FEBD3B” custom_padding=”4%|4%|4%|4%|true|true” global_colors_info=”{}”]<\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/06\/Adult-sunflower-headclipping-weevil.jpg” alt=”Adult sunflower headclipping weevil” _builder_version=”4.21.0″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” custom_padding=”4%|4%|4%|4%|true|true” border_width_all=”4px” border_color_all=”#F15625″ global_colors_info=”{}”]<\/p>\n Adult sunflower headclipping weevil. Note the shiny black body and elongated snout protruding from the head. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][\/et_pb_column][et_pb_column type=”1_2″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/06\/Adult-on-flower.jpg” alt=”Adult sunflower headclipping weevil on flower” _builder_version=”4.21.0″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n Adult sunflower headclipping weevil on a flower. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org <\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/06\/sunflower-head-injured.jpg” alt=”Sunflower head injured” _builder_version=”4.21.0″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n Sunflower head injured by sunflower headclipping weevil. Image credit: Whitney Cranshaw, Colorado State University, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.17.4″ _module_preset=”default” background_color=”#F1F1F1″ global_colors_info=”{}”][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Squiggle” _builder_version=”4.17.4″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” custom_padding=”||||false|false” saved_tabs=”all” global_colors_info=”{}”]\t\t In October, mature larvae burrow in the soil to overwinter. After pupating the following spring, adults emerge in early summer and can be observed on young buds and emerging flowers by July. Adults feed on pollen and make cuts on the stem underneath the head of the flower, causing it to droop noticeably Adults are most likely to be observed on the cut flower head since they are generally active in the summer months while the sunflowers are in the reproductive stage.<\/p>\n After mating, females produce puncture wounds on the stem below a developing flower before laying eggs in the head. Newly emerged larvae feed on flowers, pollen, and decaying tissues as they develop through four instars. Often, the flower head will fall to the ground and larvae will continue developing in the fallen head until overwintering in the soil. This species produces one generation each year and is often associated with native Heliantus<\/em> spp., especially the common sunflower (Helianthus anuus<\/em>), but will occasionally attack other related plants.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_row _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Squiggle” _builder_version=”4.17.4″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” custom_padding=”||||false|false” saved_tabs=”all” locked=”off” global_colors_info=”{}”]\t\t Feeding injuries include girdling of flower peduncles and leaf petioles, resulting in partially severed flower heads. Feeding injuries are generally aesthetic, especially in home gardens, and typically do not require management. In agricultural fields, sunflower headclipping weevil typically only affects a small portion of plants within border rows or along field margins. The percentage of clipped heads is estimated to be around 1-3%, although losses up to 25% have been recorded in individual fields in North Dakota.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.20.0″ _module_preset=”default” background_color=”#F1F1F1″ global_colors_info=”{}”][et_pb_row _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Squiggle” _builder_version=”4.17.4″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” custom_padding=”||||false|false” saved_tabs=”all” locked=”off” global_colors_info=”{}”]\t\t To monitor sunflower headclipping weevil, fields can be scouted for sunflowers that have clipped heads. In some states such as Kansas, management is recommended when weevils are observed on sunflowers and over 10% of the heads within a field are clipped. However, no specific economic thresholds have been developed, and management is not necessary when adults are only observed periodically.<\/p>\n Sunflower headclipping weevils are considered a minor pest of commercially grown sunflowers and can be difficult to manage in smaller home gardens. Injury in Colorado is usually limited to field edges and treatment is not typically necessary. In situations where treatment is necessary, the insecticide should be applied to the back of the flower heads rather than the front.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.20.0″ _module_preset=”default” background_color=”#FFFFFF” global_colors_info=”{}”][et_pb_row _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.17.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Squiggle” _builder_version=”4.17.4″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” custom_padding=”||||false|false” saved_tabs=”all” locked=”off” global_colors_info=”{}”]\t\t Charlet, L., and J. Brewer. (n.d.).<\/strong> Sunflower Insect Pest Management in North America. University of Nebraska \u2013 Department of Entomology. Available https:\/\/ipmworld.umn.edu\/charlet<\/a><\/p>\n Colorado State University. (n.d.).<\/strong> Sunflower Headclipping Weevil. Colorado State University \u2013 Extension. Available https:\/\/webdoc.agsci.colostate.edu\/bspm\/arthropodsofcolorado\/Sunflower-Headclipping-Weevil.pdf<\/a><\/p>\n Davis, H. 2020.<\/strong> Managing Insect Pests of Texas Sunflowers. Texas A&M \u2013 Extension. Available https:\/\/extensionentomology.tamu.edu\/resources\/management-guides\/managing-insect-pests-of-texas-sunflowers\/<\/a><\/p>\n Knodel, J., L. Charlet, and J. Gavloski. 2010.<\/strong> Integrated Pest Management of Sunflower Insect Pests in the Northern Great Plains. North Dakota State University \u2013 Extension Service. Available https:\/\/library.ndsu.edu\/ir\/bitstream\/handle\/10365\/9462\/e1457_2010.pdf?sequence=1<\/a><\/p>\n Michaud, P. 2013.<\/strong> Sunflower Insects. Kansas State University \u2013 Department of Entomology. Available https:\/\/entomology.k-state.edu\/extension\/insect-information\/crop-pests\/sunflowers\/sunflower-headclipping-weevil.html#:~:text=This%20is%20a%20black%20weevil,leaves%20hanging%20on%20the%20plant<\/a><\/p>\n\n
\n[\/et_pb_text][et_pb_text _builder_version=”4.24.2″ _module_preset=”default” header_2_font_size=”36px” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\nLife history and habits<\/h2>\n
\n[\/et_pb_text][et_pb_text _builder_version=”4.24.2″ _module_preset=”default” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\nInjury<\/h2>\n
\n[\/et_pb_text][et_pb_text _builder_version=”4.24.2″ _module_preset=”default” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\nMonitoring<\/h2>\n
Management<\/h2>\n
\n[\/et_pb_text][et_pb_text _builder_version=”4.24.2″ _module_preset=”default” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\nReferences<\/h2>\n