Short answer: The bird-dropping spider (Celaenia excavata) is an Australian orb-weaver relative that spends the day sitting still on a leaf, looking like a splash of bird dung. At night it builds no web. Instead it hangs from a short silk line and gives off a scent that copies the sex pheromone of female moths, then grabs the male moths that fly in. Its bite is not considered dangerous to people.
Bird-dropping spider at a glance
| Scientific name | Celaenia excavata (L. Koch, 1867) |
|---|---|
| Family | Araneidae (orb-weavers), although this species does not build an orb web |
| Other common names | Death’s head spider, orchard spider, bird-dung spider |
| Body length | Female about 12 mm; male about 2.5 mm |
| Range | Much of eastern and southern Australia, with records as far inland as Uluru; the World Spider Catalog also lists New Zealand |
| Habitat | Foliage in open woodland, orchards and suburban gardens |
| Main prey | Moths, mostly males drawn in by the spider’s scent |
| Risk to people | Bite not considered dangerous |
What is a bird-dropping spider?
“Bird-dropping spider” is a common name, not a scientific one. In Australia it usually means Celaenia excavata, the best-known member of the genus Celaenia. Several other Celaenia species exist in Australia and New Zealand, and some of them look similar. Spiders in other groups around the world have also evolved a dropping-like look, so the same name can turn up elsewhere for unrelated species.
This page focuses on C. excavata. It belongs to the orb-weaver family, Araneidae, but it has given up the orb web entirely. A large study of orb-weaver relationships published in Cladistics placed Celaenia in the same branch of the family as the bolas spiders (the “mastophorines”). Spiders in this group have all abandoned the classic orb web.
How to recognize one
An adult female is easy to spot once you know the shape. Look for these features together rather than relying on colour alone:
- Size: females have a body length of about 12 mm. Males are tiny, at about 2.5 mm, and are rarely noticed.
- Abdomen: broad and roughly triangular, dipped along the midline, with a pair of rough humps toward the rear.
- Colour: mottled brown, white and cream. Some people see a skull-like pattern, which explains the name “death’s head spider.”
- Posture: by day the legs are folded tightly against the body, so the spider looks like a lumpy blob rather than an animal with eight legs.
- No web: you will not find a large orb web around it. At most there is a little silk where it sits or hangs.
- Egg sacs nearby: a cluster of round, marbled brown balls attached to a twig or leaf is a strong extra clue.
Other Australian spiders can have knobbly or patterned abdomens, so a location, the resting posture and the absence of an orb web all matter. If you are unsure, our spider identification guide explains how to combine several clues.
Where bird-dropping spiders live
The Australian Museum describes the species as occurring across much of eastern and southern Australia, with records from Uluru in central Australia. It is found in open woodland and is moderately common in suburban gardens, where it is easy to overlook. The name “orchard spider” comes from its habit of turning up on fruit trees, where moths are plentiful.
The World Spider Catalog also lists New Zealand in the species’ range. Most of what is published about its behaviour, though, comes from Australian observations.
Why it looks like bird droppings
The disguise is a defence against predators that hunt by sight during the day, mainly birds and wasps. A small, pale, lumpy object sitting openly on a leaf is something most predators ignore. The spider adds to the effect by not moving at all. It often rests in quite exposed spots, which would be risky for a spider that looked like a spider.
This kind of protection is called masquerade: the animal resembles an inedible object rather than simply blending into the background. It only works in daylight, which fits with the fact that this spider hunts after dark.
How it hunts moths at night
Bird-dropping spiders use a lure instead of a trap. After dark, a female moves to the edge of a leaf or twig and hangs from a short silk thread with her front legs spread wide. She releases a chemical that mimics the airborne sex pheromone of female moths. Male moths following that scent fly close, and the spider seizes them with her strong front legs.
Because the lure targets males, the diet is mostly male moths. Records from different places show how the prey list depends on local moths:
- Near Brisbane, the prey recorded was only male lawn armyworm moths (Spodoptera mauritia, family Noctuidae).
- Near Canberra, where that moth is not usually found, the spiders caught two other common noctuid moths instead.
- At Canberra the spiders also occasionally caught a female moth or an unrelated species, which suggests they will grab other moths that happen to come within reach.
Bolas spiders use a similar scent trick but catch their moths with a sticky blob on the end of a silk line. Bird-dropping spiders skip the bolas and use their legs. You can read more about different hunting styles on our spider behavior and spider diet pages.
Egg sacs and males
The egg sacs are one of the most noticeable signs of this species. Each one is a marbled brown ball about 12 mm across, roughly the size of the female herself, and holds more than 200 eggs. A female can join up to 13 sacs together with silk. She stays with the cluster, sitting beside it by day or hanging below it at night while she waits for prey.
Males are only about 2.5 mm long, a fraction of the female’s size. Very little has been published about how they find females or how courtship works in this species, and how long individuals live is not well documented.
Is the bird-dropping spider dangerous?
No. The Australian Museum states that its bite is not considered dangerous. If a bite does happen, first aid is usually not needed. A cold pack can ease local pain or swelling.
If you are not sure what bit you: do not assume it was a harmless species. In Australia, call the Poisons Information Centre on 13 11 26 for advice, or 000 in an emergency. Outside Australia, contact your local poison centre or doctor. Seek medical care for severe, spreading or worsening symptoms, and do not try to catch an unknown spider to identify it.
For a wider look at how spider bite risk varies by species and region, see the spider bites and danger section.
If you find one in your garden
The best thing to do is leave it alone. It is an outdoor spider of foliage, and it spends its nights catching moths. If you want to see one, check the upper surfaces of leaves on shrubs and fruit trees during the day. Look for an object that seems slightly too neat and symmetrical to be real dung. If one needs moving, guide it into a container with a sheet of paper rather than picking it up.
Spiders like this one play a quiet part in garden food webs. Our page on why spiders are important explains more.
Frequently asked questions
Is the bird-dropping spider poisonous?
“Poisonous” is the wrong word for spiders, which inject venom through their fangs. Like almost all spiders, the bird-dropping spider is venomous, but its bite is not considered dangerous to people.
Does the bird-dropping spider make a web?
Not an orb web. It produces silk for its short hunting line and for its egg sacs, but it catches prey with its front legs rather than in a web.
Why is it called the death’s head spider?
The markings on some individuals’ abdomens can look a little like a skull.
Is the bird-dropping spider a bolas spider?
No, but they are related. Both belong to the same branch of the orb-weaver family and both attract male moths with fake scents. Bolas spiders swing a sticky silk line; bird-dropping spiders catch moths with their legs.
How big is a bird-dropping spider?
Adult females have a body length of about 12 mm. Males are much smaller, at about 2.5 mm.
For more Australian and worldwide species, browse our spider types collection.
References
- Australian Museum. Bird-dropping Spider, Celaenia excavata. Accessed November 2026.
- World Spider Catalog (2026). Celaenia excavata (L. Koch, 1867). Natural History Museum Bern. Accessed November 2026.
- World Spider Catalog (2026). Celaenia atkinsoni (O. Pickard-Cambridge, 1880). Natural History Museum Bern. Accessed November 2026.
- Scharff, N., Coddington, J. A., Blackledge, T. A., Agnarsson, I., Framenau, V. W., Szűts, T., Hayashi, C. Y. & Dimitrov, D. (2020). Phylogeny of the orb-weaving spider family Araneidae (Araneae: Araneoidea). Cladistics 36(1): 1–21. doi:10.1111/cla.12382
- NSW Poisons Information Centre. Spider bites. Accessed November 2026.
