A Not Very Hungry Caterpillar
Life is up and down at the moment with the increasing pressure of finding a new place to rent, so I’ve been throwing myself into my plants. (Not literally, of course. Although there was a dodgy moment at the nursery when I tripped over a tree root and almost landed faced first in the Eucalyptus tube stock. Luckily, I regained my balance and the Carbeen saplings escaped a flattening.)
While repotting today, I noticed that something had been helping itself to the Red Tulip Oak (Argyrodendron peralatum, Malvaceae). This tree is native to the Queensland Wet Tropics, growing in rainforest from coast to mountain tops. It is doing well in its pot. Over summer it put on a big growth spurt, but the cool, dry weather is here now and things are slowing down. The poor plant was barely keeping ahead of the leaf-eater.
As I pondered on the destruction, a shiny little face peered up at me. The shiny face was framed by two bunches of long black bristles that looked adorable but were guaranteed to make me want to rip off my skin if they made contact. Safe in its coat of irritating hair, the culprit kept chewing. Some leaves still remained.
The caterpillar belongs to a tussock moth (Lymantriinae, Erebidae), probably of the genus Orgyia. Adults are less fancy than their young — they are shades of brown and grey, they don’t feed, and the females have wings that are so short they are unable to fly. The caterpillars are where it’s all happening.
The hairs, especially the four tufts on the back and those on the sides, are barbed. When Orgyia caterpillars pupate, they arm their pupal cases with urticating hairs to protect them while they undergo metamorphosis. Because the females cannot fly, they lay their eggs in the remnants of the pupal case or close by. The first instar larvae often use silk threads to catch the breeze and drift away. Unlike many other moths and butterflies, tussock moth caterpillars are not particularly fussy about their host plants. They are happy with almost anything.
The Red Tulip Oak is struggling. It’s my fault. I had seen the youngest caterpillars grazing on the leaves of various Syzygium, especially the New Guinea Satinash (S. buettnerianum, Myrtaceae), but left them to it. They were tiny? How much damage could they do?
Now, watching the Red Tulip Oak leaves dwindle to midribs under the nibbling of a voracious caterpillar, I realise I am going to have to Do Something Soon.
But not today. The big caterpillar has had a lucky escape.