Bird-dropping spider is a member of the family Araneidae of the orb-weavers. It has a scientific name of Celaenia excavata. It is an Australian spider that is best known due to its incredible camouflage. It mimics the bird droppings, which shield it against birds and bigger predators.
The females are approximately 12 mm, and males remain small at 2.5mm. It has a triangular abdomen that is mottled with brown, white and cream. Its outline and color make it look very similar to bird waste and it blends well in its habitat.
As the Australian Museum, Entomology Department (2023) reports, Celaenia excavata uses violent mimicry based on chemicals. The spider secretes pheromones just like the female noctuid moths. These pheromones attract male moths during the night. When they come near, the spider catches them on its forelegs and eats.
| Characteristic | Description |
| Scientific Name | Celaenia excavata |
| Common Name | Bird Dropping Spider |
| Size | Females: 8–12 mm; Males: 2–3 mm. Females are significantly larger. |
| Color & Appearance |
Resembles a bird dropping when resting—white, brown, and black blotched body. Thick, lumpy abdomen with irregular textures to enhance mimicry. Perfect disguise against predators such as birds. |
| Legs | Short legs tucked under the body when resting to enhance bird-dropping mimicry. |
| Eyes | Eight small eyes; relies more on vibrations and scent than vision. |
| Habitat |
Found in woodlands, gardens, forests, and shrubs. Common in Australia, New Zealand, and surrounding regions. Prefers sheltered spots on leaves and branches where mimicry is effective. |
| Behavior |
Masters of mimicry—remain motionless during the day to avoid predators. No orb webs; instead, use strong pheromones to lure male moths. Mostly inactive and hidden during daylight hours. |
| Diet |
Primarily feeds on male moths attracted to their pheromone mimicry. Occasionally captures other small insects passing nearby. |
| Venom |
Mild venom used to subdue small insects. Harmless to humans; bites are extremely rare and non-medically significant. |
| Reproduction |
Females lay large egg sacs that resemble berries or seeds. Egg sacs hang from branches and are often guarded. Spiderlings disperse after hatching. |
| Lifespan | Approximately 1–2 years; females live longer than males. |
| Geographic Range | Australia, Tasmania, New Zealand, and nearby islands. |
| Adaptations |
Bird-dropping mimicry offers powerful camouflage from predators. Pheromone mimicry attracts prey efficiently without building a web. Ability to remain motionless for long periods increases survival. |
| Predators | Birds, lizards, wasps, and larger spiders. |
| Activity Time | Mostly nocturnal; hunts at night and remains hidden during the day. |
| Prevention Tips |
Trim shrubs and foliage near windows. Remove insects and moth-attracting lights around homes. Seal gaps around doors and windows to prevent entry. |
| How to Get Rid of Them |
Gently relocate using a container and paper. Reduce outdoor lighting that attracts moths (their prey). Keep plants and sheltered areas tidy. Professional pest control is rarely needed as they are harmless and non-aggressive. |
What are the Key Characteristics of Dropping Spiders?
Here are the six steps of the key characteristics of dropping spiders:
- Camouflage: The spider dependent on the bird dropping is the worst defense of disguise. Its white, brown, and cream triangular abdomen appears to resemble bird droppings. This look helps it to keep off the birds and other bigger birds of the day.
- Hunting Style: This spider preys on a nocturnal basis. It depends on pheromone mimicry to attract male moths by emitting scents that are similar to those of female moths. When the moth closes up, the spider traps it in fast motions.
- Diet: It feeds mostly on male moths attracted by the smell trap. It even consumes other insects that come to its resting place in the night. The specialized feeding plan provides it with a constant food supply.
- Behavior: The spider remains motionless and concealed during the day. It is also a nocturnal predator. This distinct day/night activity change makes it a night hunter that does not take risks in search of prey.
- Reproduction: In their lifetime, female spiders have multiple egg sacs. Hundreds of eggs are carried by each sac. These eggs are hatched during the warm months and this guarantees survival and spread of spiderlings in the most suitable conditions.
- Lifespan: The median life expectancy is 1 to 2 years. Females are more likely to live longer than males due to their fertility and ability to give birth to babies, whereas men die soon after mating.
Where Do Bird Dropping Spiders Live?
Here are the three habitats steps of dropping spiders:
- Habitats: The bird-dropping spiders inhabit the gardens, woodlands and forests. They also fit well in the backyards of suburbs. These locations provide shelter, food, and cover that facilitates their camouflage to make them appear natural to the environment.
- Resting Spots: They remain still on leaves, fences, or branches during the day. They are almost invisible due to their camouflage. They abandon these locations at night to hunt, and they do it with the help of pheromone mimicry to attract male moths.
- Geographic Range: The spider is active in eastern and southern Australia. It occurs in rural as well as suburban areas. Its extensive spread indicates its ability to thrive well in various habitats that have prey and shelter.
How Can You Identify a Bird Dropping Spider?
Here are five steps to identify a bird dropping spider:
- Size: Women spider dropper birds are 12 mm long in the body. Males remain considerably smaller, up to 2.5 mm. There is a deep difference in size between the sexes and this is evident within this species.
- Coloration: White, brown, and black patches appear on their bodies. These are patterns resembling bird droppings. This coloring shields them, as it disorients such predators that do not feed on debris.
- Body Shape: The body appears abnormal, bumpy, and slightly flattened. This asymmetric form increases the disguise. The shape and its colors make the spider look like a leaf, branch, or fence.
- Webs: They do not build huge circular webs like many orb-weavers. Rather, it relies on draglines to move or remains inactive until prey has moved within range of attack.
- Behavioral Clues: The spider is absolutely still during the day. It remains adhered to the leaves or surfaces like droppings. Its behavior at night is different since at night it becomes active and starts hunting.
How Can You Prevent Bird Dropping Spiders Around Your Home?
Here are five techniques to prevent bird-dropping spiders around your home:
- Trim Vegetation: Reduction in the growth of plants and shrubs around windows or porches reduces spiders hiding areas. Fewer leaves also lower the level of insect activity, which directly lowers food sources in the vicinity of habitation.
- Reduce Outdoor Lighting: During the night, outdoor lights attract moths. Moths constitute the primary prey of the bird-dropping spiders and so cutting down on light reduces the moth population, which in turn acts as a deterrent to spiders near houses.
- Clear Hiding Spots: Elimination of leaf litter, piled wood and garden waste destroys safe resting areas. The clean environment makes it difficult for spiders to remain concealed during the day.
- Seal Entry Points: Tight crevices, cracks and holes around doors and windows. Sealing these areas helps to keep the spiders out of the buildings.
- Regular Cleaning: Sweeping and wiping of outdoor surfaces also eradicates silk draglines and little shelters. Regular cleaning helps in keeping surfaces clean, minimizing the chances of spiders making a nest in such areas.
If you’re seeing spiders, schedule a same-day inspection now!
Are Bird Dropping Spiders Dangerous?
Bird dropping spiders do not pose a threat to humans and they are harmless. They are not dangerous, as their venom is created to target small insects, and not people.
These spiders show no aggression to humans and choose to stay hidden during the day. They rarely bite, even if disturbed, as their main focus is catching insects at night.
Their way of hunting also reduces the moths, so they can be useful in controlling the insects naturally. They maintain a good balance in the ecosystem by attracting and eating moths, thereby decreasing the number of pests around human settlements.
