Black Widow vs Brown Widow
Two cousins in genus Latrodectus — both venomous, but one is dramatically more dangerous than the other.
Western Black Widow
Latrodectus hesperus
Red hourglass on a black mirror. Venom 15× rattlesnake by weight. Doesn't always eat the male.
Open the file →
Brown Widow
Latrodectus geometricus
Black widow's invasive displacing sister. Spikier egg sac. Bite is milder despite stronger venom drop-for-drop.
Open the file →The short version
Western black widow (Latrodectus hesperus) and brown widow (Latrodectus geometricus) are both medically-significant Latrodectus widow spiders — but the BC-relevant species is the western black widow. Brown widow is found in the southern US and increasingly globally; if you see one in BC it almost certainly travelled in on imported goods. Both bite, both produce neurotoxic latrotoxin venom, but bite severity differs.
How to tell them apart
- 1
Color: western black widow is glossy jet-black with a vivid red hourglass on the underside; brown widow is mottled tan-brown with an orange hourglass.
- 2
Range: western black widow is widespread across western North America (including BC's Okanagan + interior, occasionally Lower Mainland); brown widow is southern US, Australia, and tropics.
- 3
Egg sac: western black widow egg sacs are smooth tan spheres; brown widow egg sacs are spiky-textured (a unique tell).
- 4
Venom severity: both produce latrotoxin, but brown widow bites are typically less severe than black widow bites — fewer systemic effects.
- 5
Web: both build messy three-dimensional cobwebs in protected outdoor sites (woodpiles, sheds, wheel wells).
- 6
BC context: see /pests/western-black-widow for the BC field-guide treatment protocol — present in the Okanagan, southern Vancouver Island, occasionally the Lower Mainland in summer.