Nacaduba biocellata
In 3 days ~20% in a week ~40%
Nacaduba biocellata, the double-spotted line blue, is a butterfly of the family Lycaenidae. It is found in Australia (including New South Wales, the Northern Territory, South Australia, Victoria and Western Australia), Singapore, the New Hebrides, Sumba and Bali.
The wingspan is about 20 mm. Adult females have a brown upperside, while the males are blue with narrow black margins. The underside of both sexes is pale brown with light and dark wavy lines. The larvae feed on the shoots, flowers and buds of various Acacia species, including A. aneura, A. betchei, A. brachybotrya, A. deanei, A. erinaceae, A. irrorata, A. karroo, A. ligulata, A. osswaldii, A. penninervis, A. rigens, A. salicina, A. sclerophylla, A. sowdenii and A. victoriae. They can have a wide range of colours depending on their host plant, including pink, orange, yellow or green. They are attended by ants, mostly Iridomyrmex species, including I. purpureus and I. viridiaeneus.
Pupation takes place in a pale brown pupa. Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Uluru-Kata Tjuta National Park | 🇦🇺 Australia | |
| 2 | Flinders Ranges National Park | 🇦🇺 Australia | |
| 3 | Hattah-Kulkyne National Park | 🇦🇺 Australia | |
| 4 | Ningaloo Marine Park | 🇦🇺 Australia |
With luck
About 10% of wildlife watchers report a Double-Spotted Line Blue sighting in Melbourne on a given day, based on 125 verified sightings from GBIF citizen-science data. It is the 116th most-seen of the 875 insects we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
September and November–January
In those months about 10% of wildlife watchers report a Double-Spotted Line Blue in Melbourne on a given day, against under 5% in February–August and October, the lowest months.
Between 11 am and 2 pm
Across all the parks we cover, that three-hour window holds the most Double-Spotted Line Blue sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 5 cities where we can rate Double-Spotted Line Blue sightings, Melbourne ranks 2nd at about 10%, level with the leaders once rounded. The best odds are in Perth (Australia, about 10%).
Same family: Lycaenidae
The closest relatives of the Double-Spotted Line Blue that you can see in Melbourne (family Lycaenidae, Gossamer-winged Butterflies) are Lesser Grass Blue (about 20%), Zizina labradus (about 10%) and Saltbush Blue (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Double-Spotted Line Blue is recorded against all the insects logged in Melbourne (125 verified sightings), 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.
