Caper white butterfly eggs on the leaves of a native passionfruit. © Mike Gillam
By MIKE GILLAM
My favourite time on the Capparis spinosa calendar is seeing the plant totally stripped of its leaves, a veritable crown of thorns and bare sticks adorned with hovering caper white butterflies. A night-flowering plant, the diurnal displays of butterflies more than compensate for the wilted offerings of the previous night.
Less concerned with nectar, caper white butterflies congregate around shrubs during the day to breed and lay their eggs. For Centralian populations the leaves of Capparis species, notably C.spinosa (native passionfruit or caper bush) and C.mitchelli (wild orange) are important food plants for the caterpillar offspring.
With delicate precision and inter-spacing the female butterfly hides her vulnerable eggs on the underside of the leaves. Within a few hours the chalk coloured eggs begin to harden and darken to a tangerine orange.
Turning the leaf over to reveal the egg clusters I took this photograph at first light with fingers trembling and my camera on a tripod. Maybe I’ve attended way too many public meetings and protests over the years because this photograph always reminds me of a quorum of officials and the hoi polloi in attendance. I’m not sure the size of the crowd or the butterfly’s interpretation of social distancing would be legal these days.
I’ve also broken with tradition this week and provided a second image to show a hawk moth’s tongue, almost as long as its wingspan. The flower has already started to wilt in the early morning light but the magnificence of its nocturnal form is still evident.
For Arrernte people the fruits of both the native passionfruit (Arrutnenge) and the wild orange are highly prized; the sweet fruit pulp is eaten and the bitter pips generally spat out. Bush caper, a domesticated and superficially very similar version of the plant is grown widely around the world in warmer climates. In Italy and Spain for instance the undeveloped flower buds and fruit are harvested and sold as a delicacy, often as bottled preserves. There is also a small caper industry in Australia mostly using, I think, the cosmopolitan version.
If you plant a Capparis spinosa I’d suggest choosing a neglected corner of your block with space for a sprawling shrub that can occupy 10m2. The plant will attract a great many beneficial insects and by extension birds and lizards. However the resulting piss ant swarm will create hostile terrain for humans of fragile disposition. So it’s probably best to keep the caper bush away from the house, verandahs and play areas.
Planting these Centralian natives pretty much guarantees a humming, chirruping, rustling microcosm of wildlife in your backyard. Add a swathe of ruby saltbush so you can watch the honeyeaters moving from the vibrant multi coloured berries to dipping their tongues as the Capparis fruits ripen and split.
If we can tear ourselves away from the next David Attenborough block-buster, take a torch out after dark when the flowers are at their best and watch the moth activity. In the moonlight, the hawk moths with their rakish wings, agility and ability to hover do feel like an ecological equivalent of hummingbirds. Enjoy the astonishing sight of their impossibly long probing tongues trailing like ribbon dancers in search of nectar.They certainly need all their speed, manoeuvrability and other adaptations to avoid predation by ever present bats.
You might have to venture out to the garden several times to see hawk moths, before the temperature drops too much. (If it was easy everybody would be doing it!) On dusk the contest can become a three-way struggle between bats and hawk moths* and with birds of prey chasing the bats. Just watching it all makes me want to return to the safety of my couch!
Without exception the caper white butterflies will soon discover your flourishing native passionfruit plant. If you want a luxuriant green unchanging plant that never shows the wear and tear of chomping caterpillars, this is not the plant for you. If we can overcome our fear of untamed Centralia, of wildly fluctuating disorder, of booms and busts, of fallen leaves or caterpillar ‘plagues’ the next generation will love us for it.
*Apart from having great hearing, hawk moths use sonic pulses, report US researchers, “to respond to bats producing the high-frequency sounds, possibly as a self-defense mechanism to jam the echolocation ability of their predators…” (Science Daily, 4 July 2013).