This is another article that didn't start with a plant, but instead with an insect! Last week we had the adventure of the non-Stink Bugs on an Illawarra Flame Tree (Brachychiton acerifolius), and this week it's the surprise appearance of a butterfly with a very specific plant relationship.

I'd long known of this butterfly, the Bright Copper (Paralucia aurifer) but never had much hope of seeing it as it is considered to be very local, associated particularly with Blackthorn (Bursaria spinosa), a beautiful shrubby tree that I don't spend nearly enough time around. The countless hours I spend pottering in the garden or in my tiny backyard nursery are not hours when I expect to see Bright Copper Butterflies, as there are no Blackthorns in the garden. Imagine my surprise then when I saw one perching cheerfully among my native ground covers! 

It took me a while to register that I was actually seeing a Bright Copper butterfly, despite its almost unmistakeable appearance, with four orange blotches set against a dark brown or black background on both upper and lower wings.

What was it doing at my place, with no Blackthorn to be seen? Had it been blown off course? Did I have a secret Blackthorn in the garden somewhere?? Off I went, down the rabbit hole of butterfly behaviour and plant preferences! And I found out all sorts of things.

Bright Copper butterflies don't only use Blackthorn as a larval food plant; they also use Orange Thorn (Pittosporum multiflorum), which is one of the most common plants in our garden. So perhaps they'd been attracted by the Orange Thorns? 

I also found out that there are three or four generations a year of this species, with adults most abundant in November and February. Three to four generations in a single year – wow!  

Their larvae are attended by ants in the Anonychomyrma genus, which help protect the larvae from predators and parasites as they develop. And I learned that male Bright Coppers appear to form leks (aggregations of males who gather to engage in competitive displays and courtship rituals, and to establish territories). Who knew?

I wonder how large their territories are? How big an area does a creature that lives for only a couple of months require? So much more to learn. 

But now to the grand finale. By unbelievable coincidence, as I wandered out into the reserve near our house to check on deer damage, what did I run into but an unexpected Blackthorn (Bursaria spinosa), growing happily beneath the giant Blackbutts (Eucalyptus pilularis) together with a mix of rainforest seedlings and masses of vines and ferns. This was a very welcome find, but it did make the question of the territory size of the Bright Copper butterflies a bit more urgent.

Were they coming over to our garden from a plant 30m away? Or were the Orange Thorns the explanation? I simply cannot tell without further investigation. 

But let it be said that the Blackthorn is a most beautiful and useful plant. Its copious flowers, generally present in late spring and summer have a heavenly honeyed scent. Its dense, thorny foliage provides a great haven for small birds. And its interesting-shaped fruit give the plant its scientific name.

'Bursa' means 'purse' in Latin, and at some point the person naming the Bursaria genus would have noted that its fruit looked like the sort of purse that was in use at the time. Not that useful to us now, as I've never seen anybody with a purse in that shape, but anyway, that's the origin of the name!  

Now I get to stake out the Blackthorn tree and see how many Bright Copper butterflies I can find on it.