[et_pb_section fb_built=”1″ admin_label=”section” module_id=”1″ _builder_version=”4.17.4″ 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” 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=”4.27.2″ _module_preset=”default” header_font=”||||||||” header_text_align=”left” header_font_size=”22px” width=”100%” module_alignment=”center” custom_margin=”3%||||false|false” custom_padding=”||||false|false” global_module=”23371″ saved_tabs=”all” global_colors_info=”{}”]<\/p>\n
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Order: Lepidoptera
Family: Pieridae<\/p>\n
Butterflie<\/span>s<\/span> of imported cabbageworm<\/span>, <\/span><\/span>commonly called the \u201ccabbage white<\/span>\u201d<\/span><\/span>,<\/span> <\/span>are active during the day and <\/span>have a wingspan of about 5 cm<\/span> (<\/span>2<\/span> inch)<\/span>. They have<\/span> <\/span>white <\/span>and yellow <\/span>wings <\/span>that have<\/span> a black border at the <\/span>tip<\/span>. <\/span>Male butterflies have one black spot in the middle of each front wing, while females have two black spots. <\/span>Their<\/span> bodies <\/span>are also <\/span>covered<\/span> with dense hair (setae).<\/span> <\/span>Larvae are green with a velvet textured appearance and have five pairs of prolegs. <\/span>Newly emerged caterpillars are 3.2 mm (0.13 inches) <\/span>long<\/span>, while m<\/span>ature caterpillars <\/span>reach a length of<\/span> about 3<\/span>1<\/span> mm <\/span>(1.2 inches)<\/span>.<\/span> <\/span>All instars except for the first have a thin yellow line running down the center of the back and may also have a series of <\/span>yellow spots<\/span> <\/span>running along each side. <\/span>Pupae are about <\/span>20 mm<\/span> long <\/span>with<\/span> <\/span>a chrysalis that varies in color <\/span>(see images). <\/span>Typically,<\/span> they are shades of yellow, gray, green, an<\/span>d brown.<\/span> <\/span>The eggs<\/span> are <\/span>roughly <\/span>0.5<\/span> mm<\/span> wide and <\/span>1 mm<\/span> long. Initially the eggs are pale white but become yellow over time. The flat end of the egg <\/span>is attached<\/span> to the leaf and the tapered end of the egg extends upward from the leaf surface.<\/span><\/span>\u00a0<\/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=”4.27.4″ _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” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/03\/larva-of-imported-cabbageworm.jpg” alt=”larva of imported cabbageworm” _builder_version=”4.27.4″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” custom_padding=”4%|4%|4%|4%|true|true” hover_enabled=”0″ border_color_all=”#F15625″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Larva of imported cabbageworm. [\/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\/03\/adult-of-imported-cabbageworm.jpg” alt=”adult imported cabbageworm” _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 of imported cabbageworm visiting a flower.\u00a0Image credit: Mary C Legg, Mary C\u00a0 Legg, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/03\/egg-of-imported-cabbageworm.jpg” alt=”egg imported cabbageworm” _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 A single egg of imported cabbageworm (note the tapered end). Image credit: David Cappaert, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/03\/pupae-of-imported-cabbageworm.jpg” alt=”pupae imported cabbageworm” _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 Pupae of imported cabbageworm. Note the considerable variation in color. Image credit: Ansel Oommen, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/03\/cabbage-with-significant-feeding-injury.jpg” alt=”cabbage with feeding injury” _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 Cabbage with significant feeding injury due to imported cabbageworm. 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=”{}”]<\/p>\n\t\t [\/et_pb_text][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” header_2_font_size=”36px” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Imported cabbageworm overwinters as a pupa on leaves of the host plant or in nearby debris.<\/span> <\/span>After <\/span>emerging<\/span> from the chrysalis, adults typically live for about three weeks and a single female butterfly can lay up to <\/span>400<\/span> eggs throughout her life. <\/span><\/span>Oviposition occurs on the undersides of outer leaves and<\/span> egg hatch occurs <\/span>in as little as four days. <\/span>The larvae develop through five instars and increase in size with each stage.<\/span> <\/span>Young larvae tend to migrate to the inner head to feed on younger leaves, which protects the caterpillars from predators and parasitoids.<\/span> <\/span>Larvae<\/span> are most active on sunny days<\/span> and<\/span> will also feed on flowers and buds<\/span> as they mature<\/span>. It<\/span> <\/span>is estimated<\/span> that the last instar <\/span>is responsible for<\/span> 85% of feeding.<\/span><\/span> <\/span><\/span>In addition to cruciferous plants, this species has <\/span>been <\/span>observed<\/span> aggregating on flowers of blue vervain (<\/span><\/span>Verbana<\/span> <\/span>hastata<\/span><\/span><\/em>).<\/span><\/span>\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n In addition to attacking cultivated plants in the mustard family, <\/span>many<\/span> <\/span>cruciferous weeds serve as host plants for this pest.<\/span><\/span> <\/span>The number of generations produced each year is <\/span>dependent on climate, with three to five generations produced in the warmer climates of California and as few as two to three generations in the cooler climates of Canada.<\/span> <\/span>In neighboring states like Utah there are three to four generations each year.\u00a0<\/span><\/span>\u00a0<\/span><\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.17.4″ _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 _builder_version=”4.27.4″ _module_preset=”default” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n In <\/span>closed-leaf <\/span><\/span>Brassica <\/span><\/span>plants<\/span>, e<\/span>arly instars <\/span>initiate<\/span> feeding <\/span>between the large veins and midribs of leaves<\/span>, while mature larvae feed on the central head<\/span>.<\/span> <\/span>On open-leaf <\/span><\/span>Brassica <\/span><\/span>plants, feeding begins on the lower leaf surface in the vicinity of the egg.<\/span><\/span> <\/span>In the absence of management, caterpillars can completely defoliate plants, leaving only stems and large veins. <\/span>The presence of irregular feeding holes that enlarge is another sign of feeding injury. In addition to attacking leaves, t<\/span>he larvae can<\/span> <\/span>bore<\/span> into the heads of certain vegetables like broccoli and cabbage<\/span>. <\/span>The head may <\/span>fail to<\/span> form entirely w<\/span>hen young plants are under significant feeding <\/span>stress<\/span>. <\/span>In addition to feeding injury, the caterpillars <\/span>defecate<\/span> <\/span>copiously which can stain and contaminate produce.<\/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=”#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 _builder_version=”4.27.4″ _module_preset=”default” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n During the day, <\/span>adults are often <\/span>observed<\/span> flying among crops <\/span>containing<\/span> <\/span><\/span>Brassica <\/span><\/span>spp<\/span>. <\/span>Plants should <\/span>be inspected<\/span> regularly for irregular feeding holes and skel<\/span>e<\/span>t<\/span>o<\/span>nized leaves. <\/span><\/span>To do this, <\/span>10<\/span> leaves can be pulled from 10 different plants<\/span> in <\/span>different locations<\/span> of the field, <\/span>giving a total of 100 leaves. The undersides of leaves can <\/span>be inspected<\/span> for small larvae and eggs, as well as large caterpillars toward the midribs of leaves or toward the center of plants.<\/span><\/span> <\/span>Larvae<\/span>\n
The imported cabbageworm is the larva of a butterfly species that attacks a wide range of cabbages and mustards. Caterpillars are green with a yellow line running along the center of their back and can defoliate entire plants when densities are high. Adults are diurnal and can often be seen flying among crops that contain suitable host plants. Image credit: David Cappaert, Bugwood.org<\/em><\/p>\nLife history and habits<\/h2>\n
Injury<\/h3>\n
Monitoring<\/h3>\n