False black widow vs Redback spider
These two are easy to mix up. Here's how to tell a false black widow from a redback spider, and whether either one bites or stings.
False black widow
Steatoda grossa
Redback spider
Latrodectus hasselti
≠The key differences
Steatoda are generally less glossy, lack the bright red dorsal stripe, and their bites are far less medically significant.
⚖︎Side by side
| False black widow | Redback spider | |
|---|---|---|
| To humans | Venomous bite | Venomous bite |
| Size | Females 6-10 mm body length; males 4-8 mm | Female body length 6-10 mm, males 3-4 mm |
| Colours | Dark brown, Purplish brown, Pale cream (faint markings) | Black, Red, Dark brown |
| Family | Theridiidae | Theridiidae |
| Habitat | Human structures (houses, basements, garages), sheds, under eaves, rock crevices and debris piles | Sheltered, dry locations near ground level: under rocks, logs, roof eaves, sheds, garages, fence posts, and in outdoor furniture or litter; also sometimes indoors in cluttered areas. |
| Range | Originally from the Mediterranean and Macaronesia region; now nearly cosmopolitan, commonly found across North America, Europe and many other parts of the world | Native to mainland Australia; introduced and established in New Zealand and reported in parts of Asia and some islands via human transport. |
| Active | Active year-round in heated buildings; outdoors most active spring through autumn and mainly nocturnal | Year-round in mild climates, most active in warmer months and at night when males search for females. |
| Pest? | Yes | No |
🔍How to spot a false black widow
- Round, smooth, shiny abdomen; body length 4-10 mm depending on sex
- Uniform dark brown to purplish coloration; may show faint pale markings but lacks bright red hourglass
- Builds irregular, tangled cobwebs in sheltered corners, often near the ground or in undisturbed indoor areas
- Compare size and markings to distinguish from related species (see similar species)
🔍How to spot a redback spider
- Adult females: shiny black or very dark brown, with a distinctive red or orange dorsal stripe or hourglass marking on the abdomen
- Female size much larger and more rounded than males; males are smaller, slender, and brownish with lighter markings
- Builds a messy, tangled web close to the ground in sheltered places; look for egg sacs and the female near the web
?Frequently asked questions
What is the difference between a false black widow and a redback spider?
Steatoda are generally less glossy, lack the bright red dorsal stripe, and their bites are far less medically significant.
Is a false black widow or a redback spider more dangerous?
False black widow: Venomous bite. Redback spider: Venomous bite. Bites are uncommon and usually occur when a spider is pressed against skin. Bites can cause latrodectism: intense pain around the bite that can spread, sweating, muscle pain and cramping, nausea, and autonomic symptoms.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.