Arachnocampa richardsae
In 3 days ~20% in a week ~30%
Arachnocampa is a genus of nine fungus gnat species which have a bioluminescent larval stage, akin to the larval stage of glowworm beetles. The species of Arachnocampa are endemic to Australia and New Zealand, dwelling in caves and grottos, or sheltered places in forests.
A previous placement was in the genus Bolitophila. This species and several related species were moved in 1924 to a new genus, Arachnocampa, meaning "spider web-worm," for the way the larvae hang sticky silk threads to ensnare prey. The genus Arachnocampa belongs in the family Keroplatidae.
Arachnocampa species have holometabolous metamorphosis with eggs, larvae, pupae, and adults. Individuals spend most of their lives as larvae. These flies live from about 6 through 12 months as larvae, depending on food availability. A larva is only about 3–5 mm long when it emerges from its egg, and can grow up to about 3 cm long.
The larva spins a nest out of silk on the ceiling of the cave and then hangs down as many as 70 threads of silk (called snares) from around the nest, each up to 30 or 40 cm long and holding droplets of mucus. The larvae can only live in a place out of the wind, to stop their lines... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Royal National Park | 🇦🇺 Australia | |
| 2 | Blue Mountains National Park | 🇦🇺 Australia |
With luck
About 10% of wildlife watchers report an Arachnocampa richardsae sighting in Blue Mountains National Park on a given day, based on 10 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 409th most-seen of the 789 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 30%, if each day is a fresh chance.
April–June, August, October and December
In those months about 10% of wildlife watchers report an Arachnocampa richardsae in Blue Mountains National Park on a given day, against under 5% in January–March, July, September and November, the lowest months.
Between 7 and 10 pm
Across all the parks we cover, that three-hour window holds the most Arachnocampa richardsae sightings with a recorded time, and about half of them come between 6 pm and 6 am: it is seen both by day and at night.
Among the best
Of the 2 parks where we can rate Arachnocampa richardsae sightings, Blue Mountains National Park ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Royal National Park (Australia, about 10%).
Same order: Diptera
The closest relatives of the Arachnocampa richardsae that you can see in Blue Mountains National Park (order Diptera, Flies) are Australian Wingless Soldier Fly (about 10%), Yellow-Shouldered Stout Hover Fly (about 10%) and Common Drone Fly (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Arachnocampa richardsae is recorded against all the insects logged in Blue Mountains National Park (10 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
