Help or hindrance?

While leaf and flower eaters can be destructive, they do prompt plants to regenerate, says MARTYN ROBINSON

Pruning is something most of us do in the garden from time to time. Usually it is to remove dead flowers to encourage the production of new blooms, or to improve the shape of a plant, or even just to trim back something that is growing too vigorously. Well, interestingly, pruning happens in nature too – for different reasons, but the effects on the plants are just the same.

The feasting habits of various foliage feeders, which encompasses everything from caterpillars to koalas, makes most plants replace the lost foliage with multiple leaves and growing points. This results in a bushier plant. Those plant eaters who prefer flowers have the same effect on their hosts, and the plant sends out many more buds to replace those it has lost. Even the seemingly pointless vegetative vandalism of a flock of cockatoos causes useful pruning in the branches of the trees they visit, while wearing down the rough edges of their beaks and perhaps exposing a wood-boring grub or two.

This is why I am always tolerant of foliage eaters in the garden, as although the plants they eat look messy for a little while, they rarely die. In fact, they usually grow back far bushier than before. A classic example of a useful pruner is the impatiens hawk moth (Theretra oldenlandiae), with its huge, ‘black with yellow spots’ caterpillars. When these finish feeding and wander off to pupate, the impatiens looks totally destroyed. But within days, new foliage and buds are forming all over the much bushier plant. So spare some grubs, and let them do some pruning work for you.

Martyn gardens mainly on Sydney’s Northern Beaches

Have you found something interesting in your garden? Send us a photo and Martyn will ID it. Email yoursay@gardeningaustralia.com.au with ‘Creature’ in the subject line.