Yes, black widows can absolutely be brown. Juvenile black widows are brown or tan with white and red markings, male black widows are often boldly patterned in lighter colors, and there is an entirely separate species called the brown widow that shares the same genus. So if you’ve spotted a brown spider with widow-like features, you’re not imagining things.
Why Young Black Widows Are Brown
The shiny, jet-black look most people picture belongs specifically to adult female black widows. Before they reach maturity, black widows of both sexes go through several molts during which their bodies are tan, brown, or grayish with distinct markings. Juveniles typically display a long red stripe running down the back of the abdomen, sometimes ending in a few red dots, along with white slash-like marks on the sides. With each successive molt, the spider darkens. By the time a female reaches full adulthood, she’s the glossy black spider everyone recognizes, but that process takes several months. During all of that time, she looks brown.
Males, even when fully mature, remain small (only about 4 to 8 mm in body length) and variable in color. They’re often boldly marked in patterns similar to those of immature females, meaning they can stay brown, gray, or mottled their entire lives. Most people never notice male black widows because they’re so much smaller and less dramatically colored than their mates.
The Brown Widow: A Separate Species
The brown widow is a distinct species in the same genus as the black widow. Female brown widows have a brown body with tan to light brown legs marked by dark brown bands. Their abdomens are highly variable, sometimes showing a mix of white, black, and orange patterns on top. The telltale hourglass on the underside is yellowish-orange to reddish-orange rather than the bright red seen on black widows.
Brown widows originally ranged across Africa and South America but have spread aggressively across the southern United States. They’re now established throughout Florida, along the Gulf Coast into Texas, Louisiana, and Mississippi, and into Georgia and South Carolina. Separate populations are established in southern California and Hawaii. If you live in any of these areas, a brown spider with an hourglass marking is very likely a brown widow rather than an immature black widow.
Telling a Brown Widow From a Young Black Widow
This is one of the trickiest identification challenges in household spider encounters, because the two look remarkably similar at first glance. Both are brown, both have patterned abdomens, and both build messy, irregular webs. But several details separate them if you look closely.
The most reliable feature is the pattern of black dots on the abdomen. On a brown widow, the diagonal light-colored stripes on the sides of the abdomen look like fingers pointing upward, each topped by a large, rectangular black blotch. On an immature black widow, those same stripes are straighter and flatter, with smaller, blobby black dots at the tips.
The central stripe running down the top of the abdomen also differs. On a brown widow, this stripe extends only about halfway up from the rear, and the forwardmost dark spot is isolated from the rest of the stripe, sitting separately and appearing about twice as wide as it is long. On a juvenile black widow, the stripe runs nearly the full length of the abdomen, the spots connect to the stripe rather than floating apart, and the forwardmost spot is longer than wide, shaped like an arrowhead.
One more easy shortcut: look for egg sacs in the web. Brown widow egg sacs are round but covered in small spikes, giving them a spiky, sea-urchin-like texture. Black widow egg sacs are smooth and papery. If you see a spiked egg sac, you’re dealing with a brown widow.
How Brown Widow Bites Compare
If your reason for searching is that you found a brown widow-looking spider and want to know how worried to be, the answer is: less worried than you’d be about a true black widow, but still cautious. Drop for drop, brown widow venom is as toxic as black widow venom. The difference is that brown widows appear to inject far less of it per bite. A study of 15 verified brown widow bites in Africa found that none of the victims developed the classic full-body symptoms (muscle cramps, sweating, elevated blood pressure) associated with black widow envenomation. The two main symptoms were pain at the bite site and a red mark.
That said, at least one documented case did involve more serious symptoms requiring hospitalization, so brown widow bites aren’t entirely harmless. They’re just far less likely to cause a systemic reaction than a bite from a full-sized black widow.
Quick Identification Checklist
- Adult female black widow: Shiny black body, bright red hourglass underneath, round abdomen, about half an inch in body length.
- Juvenile black widow: Brown or tan with red stripe and white slashes on the abdomen. Central dorsal stripe extends nearly the full length of the abdomen. Arrowhead-shaped forward spot.
- Male black widow: Small (under a third of an inch), variable color, often brown or gray with bold markings similar to juveniles.
- Brown widow: Brown body, banded legs, yellowish-orange hourglass, highly variable abdominal pattern. Dorsal stripe extends only halfway up. Spiky egg sacs.
If you can safely flip the spider over (or view it through the web from below), the hourglass color is your fastest clue. A red hourglass points to a black widow at some life stage. An orange or yellowish-orange hourglass points to a brown widow. Combine that with the egg sac texture and the abdominal stripe length, and you can make a confident identification without needing to be an entomologist.