Latrodectus hesperus [Western Black Widow] Details

Latrodectus hesperus [Western Black Widow] Details

Western Black Widow scientific name Latrodectus hesperus Chamberlin & Ivie. Commonly known as Western Black Widow Spider or Western Widow is a venomous spider generally found in western region of North America. L. hesperus very similar looking with L. mactans. They live in warmer region of United state and desert of American southwest.

Scientific Name – Latrodectus hesperus

Western Widow spider female 14-16 mm long (only body size not including legs). Male approximately ~1/3 inch (7-8 mm not including legs) half the size of female. Western Black widow female’s body is about half inch long. Female have complete hourglass mark on lower abdomen. Usually completely black except for a tiny reddish spot near tip. When L. hesperus female & male grow older, gradually develop into shiny black or dark color.

Latrodectus hesperus

Western Black Widow Spider Facts

Western Widow Venom – L. hesperus one of the venomous spider and venom 15 times toxic than rattlesnake. Generally female spider can bite humans and release neurotoxin. ‘

Western Widow Spider facts – Female have 14-16 cm body size and male have 7-8 mm body size. Male spiders less than half size of female. Males have three pale strips on each side of abdomen (light brown in color). Immatures – spiderlings of both male & female have same coloration. Also characteristic pattern of two opposite triangle.

Latrodectus hesperus
Latrodectus hesperus
Kingdom Animalia
Phylum Arthropoda
Class Arachnida
Order Araneae
Family Theridiidae
Genus Latrodectus
Species L. hesperus

Western Black Widow Spider Life Cycle Maturity time varies & dependent on temperature and food (prey). Male wander around in search of female and at this time they do not bite or feed. Male western black widow spin small web. Then he place a drop of sperm on web, he takes sperm into special receptacles on end of his pedipalps.

Western Black Widow Spider

After Female & male mate, Western Black Widow Female Spider lays several bunches of eggs. Sac contain 750 eggs and first bunch of eggs suspended on web. Single egg sac about 1 cm in diameter and can be tan to white in color. A female western widow spider make 4-9 egg sac in summer. Incubation about 14 days. Only 1-12 spiderlings actually live from an egg sac. Development period 3-8 months and mature spider live up to one & a half year.

Black Widow Spider Western facts 

They prefer warmer regions of United states

Western Black Widow Spider Habitats – They live under rocks, plants, debris, ledges, usually built web near to ground. Sometimes built web around houses. When weather change from warm to cold, they built web inside houses. Habitat region – temperate, terrestrial. Terrestrial biomes – desert or dune. Other – agricultural, suburban, urban.

Abdomen marking – At globose abdomen red marking, that vary from complete hourglass to separate triangles. Immature have white abdomen, tan legs and black spots on body.

Western widow web of very tough fibers near a retreat mature female can hides during day time. Fibers are larger in size and they make audible sound when ripped.

Western Female Black Widow also known as combfoot spiders for family.

Female & male L. hesperus not aggressive & bite very rarely. Remain in their web unless forced to out

Western Black Widow Bite

Mature females of western widow generally round with bulbous abdomen. Mature female distinctively shiny and dark colored (black to dark brown). How Black Widow spider distinguishably identified – presence of hourglass pattern. Pattern can be highly variable with the western widow.

L. hesperus venom 15 times stronger than rattlesnake. They bite human when not within web (bite very rarely) and in defense or disturbed. Western Widow spider release neurotoxin and affect Central Nervous System. Muscle ache, chest pain and tightness are main reaction to the widow toxin.

They prefer to spin web near ground – dry, dark and peaceful area. They are potentially harmful to humans. Widow spider bite using pair of fangs. Also Bite came go unnoticed to often produce sharp pin prick pain. Redness, swelling may soon develop at affected area.

Western Black Widow Spider Bite Symptoms & Reactions

Reaction – Muscle pain, Chest pain, Speech difficulty, tightness,

Also Abdomen pain, nausea, producing stomach cramping.

Other reactions – Anxiety, restlessness, sweating, breathing difficulties, burning in soles of feet.

Symptoms and reaction increase during first day and decline day by day. but continue for several days to weeks.

About Southern Black Widow Spider – Latrodectus mactans

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