[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=”4.24.1″ _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: Araneae
Family: Sicariidae<\/p>\n
The brown recluse spider is uncommon and frequently misidentified in Colorado. These spiders can have light or dark brown bodies and are about the size of a quarter with legs extended. One distinguishing feature of this species is the violin-shaped mark on the back of the cephalothorax, the body segment that contains the head and legs. The legs of the brown recluse spider are very long, not banded, and are thought to have a silky appearance since large hairs are not present. The egg sac is less than 2.5 cm (1 inch) in diameter and contain about 40-50 small yellow eggs. Incidences in Colorado typically result from unintentional transport of brown recluse spiders from infested areas.<\/p>\n
In Colorado, funnel weaver spiders, cellar spiders, and wolf spiders are commonly mistaken for brown recluse spiders. However, unlike most spiders in Colorado, brown recluse spiders have three pairs of eyes instead of four. More information on spiders commonly found in Colorado homes is available here<\/a>.<\/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=”4.22.2″ _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\/10\/adult-brown-recluse-jpg.webp” alt=”bed bug infestation” _builder_version=”4.22.2″ _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 brown recluse spider. Notice the violin-shaped markings on back. Image credit: Lisa Ames, Univeristy of Georgia, 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\/10\/adult-brown-recluse-closeup-jpg.webp” alt=”bed bug bites” _builder_version=”4.22.2″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n Adult brown recluse spider. Notice the violin-shaped markings on back. Image credit: Lisa Ames, Univeristy of Georgia, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/10\/adult-brown-recluse-fullest-jpg.webp” alt=”bed bug eggs” _builder_version=”4.22.2″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n Adult brown recluse spider. Image credit: Lisa Ames, University of Georgia, Bugwood.org<\/em><\/p>\n [\/et_pb_blurb][et_pb_blurb image=”https:\/\/agsci.colostate.edu\/agbio\/wp-content\/uploads\/sites\/127\/2023\/10\/brown-recluse-bite-jpg.webp” alt=”bed bug eggs” _builder_version=”4.22.2″ _module_preset=”default” body_line_height=”1.4em” image_icon_custom_margin=”||-22px||false|false” global_colors_info=”{}”]<\/p>\n Bite inflicted by a brown recluse spider. Note the sunken appearance of the blister. Image credit: USDA Forest Service – Coeur d\u2019Alene Field Office, 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=”4.24.2″ _module_preset=”default” header_2_font_size=”36px” header_3_font_size=”26px” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n The immature spider reaches adulthood about a year after hatching and lives one to three years as an adult. After laying eggs, female spiders guard egg sacs until they hatch after one month. The spiderlings undergo five molts before developing into adults. An individual brown recluse spider can live two to four years and can live up to six months during periods of extreme drought or when food is absent.<\/p>\n Outdoors, brown recluse spiders live under rocks, logs, in wood piles, or other protective areas. They actively hunt at night and do not use webs to capture prey. In homes, brown recluse spiders like to live in dark, undisturbed areas such as basements, sheds, or garages. They are not active during the day and will hide in their webs in dark areas.<\/p>\n Brown recluse spiders have venom that causes tissue death, but the amount of venom introduced during the bite is controlled by the spider. The venom\u2019s toxicity varies between species.<\/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” global_colors_info=”{}” locked=”off”]<\/p>\n\t\t [\/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>\n It is impossible to diagnose a brown recluse spider bite from the wound alone, as many medical conditions produce similar necrotic-looking sores. Bites inflicted by the brown recluse spider are initially painless until several hours later when the affected area becomes red, swollen, and tender. In most cases, the bite will heal in several weeks with no further medical intervention. In more extreme cases, a necrotic lesion with a dry, sinking blue patch, central blister, and irregular edges may develop and expand several inches over days or weeks. The ulcer can persist for several months and leave a deep scar. Severe reactions to brown recluse bites tend to occur in children, the elderly, or individuals in poor health. When bitten by a brown recluse spider, it is recommended to apply ice, elevate the affected area, and seek medical attention immediately.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.22.2″ _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” global_colors_info=”{}” locked=”off”]<\/p>\n\t\t [\/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>\n Any dark, undisturbed area can harbor brown recluse spiders, and reducing clutter will limit the number of hiding places. Further management is typically not required in Colorado where brown recluse spiders are extremely rare.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.22.2″ _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_blurb title=”CSU Extension Fact Sheet” url=”https:\/\/extension.colostate.edu\/topic-areas\/insects\/brown-recluse-spiders-in-colorado-recognition-and-spiders-of-similar-appearance-5-607\/” use_icon=”on” font_icon=”||fa||900″ icon_color=”#F15625″ image_icon_width=”36px” _builder_version=”4.22.2″ _module_preset=”default” header_level=”h2″ header_font_size=”36px” locked=”off” global_colors_info=”{}”]<\/p>\n Download or view the CSU Extension’s PDF fact sheet for your reference.<\/p>\n [\/et_pb_blurb][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=”{}” locked=”off”]<\/p>\n\t\t [\/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>\n Hu, X. 2022.<\/strong> The Brown Recluse Spider: Facts and Control. Alabama A&M Extension. Available https:\/\/www.aces.edu\/blog\/topics\/home\/the-brown-recluse-spider-facts-control\/#:~:text=Life%20Cycle,300%20eggs%20during%20the%20summer.<\/a><\/p>\n\n
Life history and habits<\/h2>\n
Bites<\/h2>\n
Management<\/h2>\n
References<\/h2>\n