By James Wall
There are times when some of us want to destroy caterpillars. I know those ones on the broccoli in February are really annoying. There is however a couple of nurserymen who love caterpillars on their plants. In fact they grow them especially to feed the caterpillars. This is what I discovered behind the scenes at the Melbourne Zoo. It is all part of the butterfly enclosure and its ongoing breeding cycle that takes place so we can enjoy these wondrous creatures everyday of the year.
What you need to do as a butterfly plant grower at the zoo, is reproduce the 6 or 7 different plants, each one for the 6 or 7 different varieties of butterflies bred. You see they are very fussy and each type of butterfly will only lay their eggs on a particular plant. If the butterfly is a tropical variety, then the plant needs to be a tropical plant, meaning growing it in a greenhouse for many months of the year here in Melbourne. Now it is no good having one big batch of plants ready at once. You need to have some ready for the butterflies, some half ready, and some freshly cut back so they will be ready in a couple of months time. No plants ready equals no butterflies, so the pressure is always on, especially in winter. It’s a bit like growing lettuce all year round in your vegetable garden. You don’t plant a whole lot at once. Eight plants every second week and you will have lettuce all year round.
Some butterflies like poisonous plants like oleander. Apparently the caterpillar themselves will contain some of these toxins, and can make a predator that eats them very sick. They will think twice before eating that same colour caterpillar again. Its sort of weird how this one being eaten now, will save one of his mates in the future.
One of the plants grown is the common old Lisbon Lemon. This is used to reproduce the Orchard Butterfly, its caterpillar pictured above. It’s not the most spectacular butterfly, but of course the spectacular butterflies eat the much harder plants to grow. Of course a lemon tree chomped like the one pictured actually means a job well done.
Plants are placed in the main enclosure which is at a beautiful temperature if you like a 28 degree average. Once the eggs are laid, the plant is taken into another enclosure where caterpillars hatch and begin to eat the host plant. The caterpillar then forms a pupa or chrysalis which is like a cacoon inside which it forms into a buttefly. Often in the wild, this pupa is well camouflaged. At this chrysalis stage they are removed from the plant and hung in their own little box made of insect screen walls so as to protect them from potential predators like rats.
They are then released into the main butterfly enclosure and as we saw, midweek mums with prams, toddlers and lattes emerge in large flocks, all enjoying the magnificence of the beautiful butterflies. For me there was the extra appreciation, as before this day, I had never considered the laborious horticultural process that helped make the butterflies grow. Each butterfly only lives for about a month, But their life cycle goes on and on forever.