Celaenia excavata
Bird-Dropping Spider Identification Australia: Celaenia
Native Australian Celaenia excavata with a lumpy bird-dropping disguise, folded legs, moth-luring night hunt and distinctive round egg sacs.
Usually low riskThe common Australian bird-dropping spider, Celaenia excavata, is an orb-weaver relative that has abandoned the familiar circular capture web. The adult female is the conspicuous form: up to about 12 mm long, mottled cream, brown and black, with a broad triangular abdomen, a concave midline, two roughened rear humps and legs folded tightly against the body by day. That shape and posture resemble an unappetising bird dropping. At night she hangs from a short silk line, extends her front legs and chemically mimics a female moth signal to attract male moths within grabbing range. Large marbled-brown spherical egg sacs are a useful supporting clue, but other Australian spiders also mimic droppings, so colour or a lumpy outline cannot prove the species.
Quick identification
- Adult female body up to about 12 mm; adult male only about 2.5 mm
- Broad triangular abdomen with a concave centre and two rough rear humps
- Cream, brown and black mottling with the legs folded tightly against the body by day
- Large round marbled-brown egg sacs may hang together from foliage
- No orb capture web; the female hunts moths from a short silk line at night
What to check next
Take a directly overhead photograph, then a side view showing the abdomen humps and folded legs. Include any suspended egg sacs and a wider habitat frame, and record body length separately from the egg sacs.
When to seek medical help
Australian Museum says this spider’s bite is not considered dangerous. For an unexpected bite, wash the area and use a wrapped cold pack for pain or swelling; seek medical advice if symptoms are severe, persistent or worsening, and call Triple Zero (000) for signs of anaphylaxis.
Where it is usually seen
Foliage in open woodland, dry sclerophyll forest, orchards, agricultural areas and urban gardens, including fruit trees and shrubs where moths occur.