Latrodectus geometricus (Brown Widow Spider)

About Latrodectus geometricus

Taxonomic Hierarchy

→ Kingdom: Animalia
→ Phylum: Arthropoda
→ Class: Arachnida
→ Order: Araneae
→ Family: Theridiidae
→ Genus: Latrodectus
→ Species: Latrodectus geometricus

Common Name (Official / AAS)

Brown Widow Spider

Other Common Names

Brown Button Spider, Geometric Button Spider, Gray Widow

Author

Author of species name: Carl Ludwig Koch. First year published: 1841, as Latrodectus geometricus.

Pronunciation

laa-tro-DEK-tuhs jee-oh-MEE-trih-kuss

Meaning

The genus name Latrodectus appears to be a Greek compound that Charles Walckenaer intended to mean “biting in secret” (Cameron 2005); this likely refers to the painlessness of the initial bite and the fact that it often goes unnoticed until symptoms present. As for the specific epithet, geometricus, C. L. Koch didn’t mention what his intended meaning was, but we assume it is a Latin adjective meaning “geometrical.” It is probably to describe the fairly geometric pattern on the spider’s abdomen.

Identifying Traits of Latrodectus geometricus

Size

Body length (excluding legs) of adult female ranges from 7-10 mm; adult males range from 2-3 mm.

Female Primary Colors

Male Primary Colors

Eye diagram of Latrodectus geometricus

Eyes

Total of eight eyes; when viewed from the front, appears as two horizontal rows of four. The lateral eyes are completely separated from each other, which is a feature that can be used to distinguish true “widows” (genus Latrodectus) from the “false widows” (genus Steatoda). The secondary eyes may appear white or silver because of a light-reflecting, crystalline structure inside them called a “tapetum.” In spiders, the anterior median eyes (middle pair in the bottom row) are considered the primary eyes, while the others are considered “secondary.”

Legs

Front pair of legs is longest, third pair shortest, typical of the family Theridiidae. Legs long in proportion to body and lack obvious spines; typically light brown banded with black at the joints (banding less noticeable or absent in males). Some entirely black or dark gray females have been recorded, though it is usually possible to tell them apart from female “black widows” by the faint leg banding that is still slightly visible. Tarsi (tips of legs) have 3 claws.

Body

Most mature specimens have the abdomen entirely golden brown or silvery gray with dorsal spots of orange or white and lateral white stripes with black spots (black spots larger than in Latrodectus hesperus). The carapace is dark brown. There is also a dark form of this species, in which the females appear almost entirely black or dark gray (check for faint leg banding to separate those from “black widows”). Abdomen of mature females is usually globose, much larger than the cephalothorax. Abdomen of males is smaller, more oval, and tapered toward the rear. Both genders have an orange-red hourglass marking present on the underside of the abdomen.

Range of Latrodectus geometricus

Latrodectus geometricus can be found in the following states, provinces and territories across the United States and Canada. Our current understanding of each spider's distribution is drawn from numerous scientific publications and online spider submissions, in order to be as accurate as possible. It is important to remember that spiders do not adhere to the territorial lines decided on by humans, therefore these ranges are subject to change.

United States

Canada

Species not seen in Canada.

Additional Information

Habitat

This spider may be common in yards and gardens, sometimes building its web in more exposed situations than other species of Latrodectus. Be careful handling objects that have been undisturbed outdoors for long periods, such as children’s toys and playground equipment, gardening pots, lawn furniture, buckets, trash cans, etc. This spider’s affinity for man-made structures allowed it to spread via commerce; plus, it is very prolific.

Web

The Brown Widow spins an extensive, tangled, three-dimensional “cobweb” snare. The threads are extremely strong and elastic, and can be plucked like guitar strings without breaking. The lines anchored to the ground (or lowermost substrate) are the trap lines. Insects, or other spiders, that trip the lines become entangled. The rebounding silk yanks the victim into the body of the web where the spider apprehends it. Flying insects may also be intercepted by the body of the web. At rest, the spider usually retires into a funnel-like retreat in a crevice or beneath an object. The spider may also rest upside down in the body of its web at night. Webs are frequently associated with man-made structures in the United States.

Season

Mature individuals may be found in nearly all seasons.

Food

Prey is almost any insect or spider or other small animal that becomes entangled in the snare. There is at least one record of a small toad becoming entangled in a brown widow web and subsequently killed.

Lifecycle

Egg sacs are nearly spherical, brown or beige tufted objects that may be the best clues in identifying this species when the spider itself is not present. Each one is roughly 10 millimeters in diameter and contains anywhere from 80-150 eggs, each female producing up to 20 sacs in her lifetime.

Remarks

This species is a potentially dangerous spider, though it is timid and non-aggressive. Its venom is neurotoxic, and while it is likely to be as virulent as that of other widow spiders, bites usually result in only localized pain and swelling. The “Common House Spider,” Parasteatoda tepidariorum, is frequently mistaken for the Brown Widow, but the Common House Spider lacks the red or orange hourglass marking on the underside of its abdomen. The eye arrangements are also different and the two species create different shaped egg sacs, as well (one teardrop-shaped, the other round and tufted/spiked).

Pictures of Latrodectus geometricus (Brown Widow Spider)

General

Female Spiders

Male Spiders

Filtering options are grayed out when we do not have pictures for the given perspective. If you are a spider photographer, you can submit pictures of spiders to help fill any voids in our ever expanding library.
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Ventral
  • City/Region: Redondo Beach
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Lateral
  • City/Region: Redondo Beach
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Ventral
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Attributes: Egg Sacs
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Attributes: Egg Sacs
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Immature
  • Attributes: Dorsal
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Immature
  • Attributes: Lateral
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Immature
  • Attributes: Dorsal
  • City/Region: NE
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Lateral
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Lateral
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Ventral
  • State: Georgia
  • Country: United States
  • Latrodectus geometricus
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: Hobe Sound, Martin County
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Immature
  • Attributes: Ventral, Webs
  • City/Region: Anglevillas
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Attributes: Egg Sacs, Webs
  • City/Region: Vero Beach
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Lateral
  • Country: Bahrain
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Ventral
  • Country: Bahrain
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Lateral, Webs
  • Country: Bahrain
  • Latrodectus geometricus
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Ventral, Webs
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Lateral
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Lateral
  • City/Region: Riverside County
  • State: California
  • Country: United States
  • Latrodectus geometricus
  • Attributes: Egg Sacs
  • State: Florida
  • Country: United States
  • Latrodectus geometricus
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Egg Sacs, Webs
  • City/Region: Chattanooga
  • State: Tennessee
  • Country: United States

References and Further Reading

Various Research Papers

Scientific Diagrams and Keys for Identification

References for the Casual Reader

Species guide last updated: April 25, 2016

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