[et_pb_section fb_built=”1″ admin_label=”section” _builder_version=”4.16″ global_colors_info=”{}”][et_pb_row column_structure=”1_2,1_2″ admin_label=”row” _builder_version=”4.16″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” width=”100%” global_colors_info=”{}”][et_pb_column type=”1_2″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_text admin_label=”squiggle-left” _builder_version=”4.24.1″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” width=”75%” module_alignment=”left” custom_margin=”||||false|false” custom_padding=”||||false|false” global_module=”23371″ saved_tabs=”all” global_colors_info=”{}”]<\/p>\n
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Order: Hymenoptera The wheat stem sawfly is a prolific pest to wheat in Colorado, causing extensive damage in the eastern <\/span>parts of the G<\/span>reat\u00a0<\/span>P<\/span>lains<\/span><\/span>. A<\/span>dult wheat stem sawfly measures about<\/span> 1.9 cm (3\/4 <\/span>inch) long with smoky-brown wings. It is wasp<\/span>\u2013<\/span>like in appearance, with a shiny black body with three yellow bands around the abdomen.\u202fSawfly larvae are cream colored, have a broad head, and are<\/span> 1.3-1.9 cm (1\/2-3\/4 inch<\/span>)<\/span> long when fully grown.<\/span>\u00a0<\/span><\/span><\/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=”4.21.0″ _module_preset=”default” header_level=”h3″ header_font=”|||on|||||” header_text_align=”center” header_font_size=”26px” background_color=”#FEBD3B” custom_margin=”|4%||4%|false|true” custom_padding=”4%|4%|4%|4%|true|true” global_colors_info=”{}”]<\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/divi-agbio\/wp-content\/uploads\/sites\/127\/2022\/03\/wheat-stem-larva-ruler.jpeg” alt=”Three species of white grubs.” _builder_version=”4.21.0″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” custom_margin=”||||false|false” custom_padding=”||||false|false” global_colors_info=”{}”]<\/p>\n Wheat stem sawfly larva next to a ruler. Image credit: Daren Cockrell, Colorado State University<\/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\/divi-agbio\/wp-content\/uploads\/sites\/127\/2022\/03\/wheat-stem-sawfly-2.jpeg” alt=”Masked chafer adults.” _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 wheat stem sawfly. Image credit: Pest and Diseases Image Library, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2024\/01\/WSS-larva-in-stem-jpg.webp” alt=”Japanese Beetle Larva.” _builder_version=”4.24.0″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n What stem sawfly larvae in stub. Image credit: Adam Osterholzer and Gabriel Alnajjar, Colorado State University<\/em><\/p>\n [\/et_pb_blurb][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.16″ _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 _builder_version=”4.21.0″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n\t\t <\/p>\n The wheat stem sawfly produces one generation per year. The larvae develop entirely inside wheat stems and overwinter as larvae in the stem stubs left behind after wheat is harvested. Adults emerge in late May or early June and are generally active when winds are calm and field temperatures are above 50\u00b0 F.\u202fFemales lay eggs immediately upon emergence and typically live about one week. The adult emergence and flight period continues for 3-6 weeks.\u202fFemales lay an average of 30-50 eggs, depending on the size of available host stems.<\/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=”4.16″ _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 _builder_version=”4.21.0″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n\t\t The most visible sawfly injury is stem breakage or lodging.\u00a0<\/span>When\u00a0<\/span>wheat stem sawfly\u00a0<\/span>larvae<\/span>\u00a0mature<\/span>,<\/span>\u00a0they move down towards soil level and cut a V-shaped notch around the interior of the stem<\/span>. This\u00a0<\/span>often\u00a0<\/span>causes\u00a0<\/span>breaks at this weakened notch just prior to harvest<\/span>.<\/span>\u00a0<\/span>Some yield loss is caused by the larvae feeding on the internal stem tissue, but\u00a0<\/span>the majority of<\/span>\u00a0losses are from lodging<\/span>, which can result in yield loss of five to ten percent due to unrecoverable wheat heads that the combine cannot pick up.\u00a0<\/span>Wheat stem sawfly are primarily pests of winter and spring wheat, but can be found in triticale, barley, wheat grasses, and many native grass species found in\u00a0<\/span>Colorado grass<\/span>land<\/span>s<\/span>. They\u00a0<\/span>can<\/span>not\u00a0<\/span>complete their\u00a0<\/span>develop<\/span>ment<\/span>\u00a0in rye, corn, or millet.<\/span><\/span><\/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=”4.16″ _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 _builder_version=”4.21.0″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n\t\t To verify presence of the sawfly in a suspected plant, split the stem from top to bottom; the larva will most likely be in a chamber within the stem, just above the crown.\u00a0<\/span>Solid stem varieties of wheat have been shown to be effective in reducing damage caused by the wheat stem sawfly.\u202f<\/span>Several solid stem varieties that are adapted to Colorado are commercially available including Fortify SF and Amplify SF. There are two economically important parasitic wasps of wheat stem sawfly that have been found to significantly reduce populations in other states, however\u00a0<\/span>their populations in Colorado\u00a0<\/span>in recent years (20<\/span>17<\/span>-2021) have been relatively<\/span>\u00a0<\/span>small<\/span>\u00a0and of low economic relevance<\/span>.\u00a0<\/span>There are currently no insecticides\u00a0<\/span>that can penetrate the stems of wheat and suppress\u00a0<\/span>wheat stem\u00a0<\/span>sawfly,<\/span>\u00a0however this is an active area of\u00a0<\/span>research<\/span>.\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.21.0″ _module_preset=”default” background_color=”#FFFFFF” 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_blurb title=”CSU Extension Fact Sheet” url=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/01\/wheatstem-sawfly-factsheet-accessible.pdf” use_icon=”on” font_icon=”||fa||900″ icon_color=”#F15625″ image_icon_width=”36px” _builder_version=”4.21.0″ _module_preset=”default” header_level=”h2″ header_text_align=”center” header_font_size=”36px” global_colors_info=”{}”]<\/p>\n Download or view the CSU Extension\u2019s PDF fact sheet for your reference.<\/p>\n [\/et_pb_blurb][et_pb_text _builder_version=”4.21.0″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n\t\t Colorado State University. 2014.\u00a0<\/strong>Wheat Stem Sawfly: A New Pest of Colorado Wheat – 5.612. Colorado State University – Extension.\u00a0Available\u00a0https:\/\/extension.colostate.edu\/topic-areas\/insects\/wheat-stem-sawfly-a-new-pest-of-colorado-wheat-5-612\/<\/a><\/p>\n Varenhorst, A., P. Rozeboom, P. Wagner, and A. Bachmann. 2022.<\/strong> Wheat Stem Sawfly: An Overview. South Dakota State University – Extension. Available https:\/\/extension.sdstate.edu\/wheat-stem-sawfly-overview<\/a><\/p>\n
Family: Cephidae<\/span><\/p>\nDescription<\/h2>\n
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Life history and habits<\/h2>\n
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Injury<\/h2>\n
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Further reading<\/h2>\n