How to Identify the Red Back Spider

Learn how to identify the Red Back Spider, which is found throughout Australia and is related to the Black Widow of the United States. Red Back spiders tend to hang out in populated areas and thrive in warm areas and where there is plenty of food.

Difficulty: Moderate

Instructions

Things You'll Need:

• Ruler with mm and cm measurements
• Magnifying glass
• Gloves

1. Determine whether the spider is a female or male by identifying the color of the abdomen.

2. 
   Female Red Back. Photo by M Gray © Australian Museum

   Look at the upper abdomen of the spider. A female Red Back spider is usually black (or occasionally a brown color) and has an orange longitudinal stripe which runs into a red color. Sometimes the stripe will appear broken. The female Red Back spider will also have an "hourglass" shaped spot of red and orange on the underside of the abdomen. The full grown female Red Back has slim legs and is approximately 1 cm long, the size of a large pea. If it is a young female Red Back, the spider will have white markings on the abdomen.

3. 
   Male Red Back, photo by M Gray © Australian Museum

   Identify a male Red Back, which has less identifying marks than the female Red Back. The male is light brown and has white marks on the abdomen's upperside. The male has an "hourglass" shape on its underside like the female, however, the coloring and shapes are pale. The male Red Back is approximately 3 to 4 mm long.

4. 
   Reb Back Spider Web. Phot by Mike Gray

   Identify the web of a Red Back spider. Look for funnel-like webs with strands of sticky silk threads hanging from the bottom.

Tips & Warnings

• Red Back Spiders are poisenous, although the juvenile spiders are too small to cause any damage. If you are bitten, get medical attention immediately. In most cases, anti-venom treatment is not needed, but it is better to be safe than sorry.

Resources

• Australian Government Website