Friday, March 30, 2012

Bugs in my Garden

Most of my garden is dedicated to indigenous plants, but I have reserved a small area for food plants. We have a little lemon tree “growing” in a pot. “Growing “ because in the 3 years we have had it I don't think it has gained even 1cm. Every year it gets attacked by caterpillars that strip it bare of all it's leaves and the poor thing then expends all it's energy just trying to survive. This year when the caterpillars appeared I was armed with my camera.

They start off looking like this, and are known as Orange dogs, they are meant to resemble bird droppings and thus not look like a tasty meal to any hungry birds.

As they grow they change into these big fat green ones with beautiful markings. If you touch one it rears up and 2 “horns” protrude out of it's head, again a defence mechanism meant to ward off birds. Besides birds these caterpillars also fall prey to wasps, who lay their eggs inside the caterpillar to provide food for their young when they hatch.

The few that manage to survive all these perils eventually emerge from their pupa as the beautiful Citrus swallowtail butterfly.

Knowing this would be my reward I think will justify my recent crazy behaviour. As I mentioned I was keeping a close eye on the caterpillars and before work one morning I could see that almost all the leaves were demolished on my little tree. I had been browsing my books and the internet to find suitable indigenous plant hosts, having identified a few I tried to find some at our local nurseries – no luck. In desperation I sent my son to buy another lemon tree, with instructions to carefully transplant the hungry caterpillars. He told me that the nursery had offered to sell him pesticide to control caterpillars – he wisely declined! The next morning however when I went to look at their progress I could only find 1 of the original 6. I found 2 lying dead on the ground – then it struck me, the nursery must have treated the tree with their terrible poison. I hastily washed off the leaves in an effort to save the remaining caterpillar and I also found one starving little one on the original tree. It has been fun and enlightening to watch their progress, but alas both have since fallen prey to birds. With all these natural predators I hardly think gardeners need to kill them also, in most cases if your trees and shrubs are large and healthy then most insect attacks will not cause any lasting damage, even my little lemon is already sprouting new leaves.

Gardening to me is more than just healthy looking plants, it's about a healthy ecosystem. that means that caterpillars are important as they eventually become butterflies. Even the spiders that venture into my house and have occasionally joined me in the shower are carefully removed and returned to the garden where they aid in the control of pests.
Rain Spider
Rain Spider nest

My daughter spotted this nest hanging in the garden, a quick Google search identified it as the nest of the rain spider. (Palystes castaneus) It takes the female about 3-5 hours to construct this nest which is a little larger than a tennis ball, she stays close to the nest until the spiderlings emerge about 3 weeks later. Although rather large and scary looking these spiders are quite harmless. Mostly they confine themselves to the garden where they go unnoticed, but occasionally in the rainy season they will venture into the house. They do a wonderful job controlling insects including cockroaches but they do unfortunately include the occasional lizard or gecko in their diet as well.

Next time you spot one of these don't swat it, stop and look. It belongs to the family Mecoptera (Hanging flies) and mosquitoes form a large part of their diet.

Another useful mosquito predator is the dragonfly.

I think this one is known as a Blue Emperor (Anax imperator) belonging to the Hawker (Aeshnidae) family of dragonflies. This is the female busy laying eggs which are actually inserted into aquatic plants.

I believe that every creature in my garden serves a purpose and that if you destroy even one then you upset the balance of nature and will ultimately pay the price. Taking the time to learn about the creatures in the garden just adds to the pleasure of gardening and also provides an invaluable learning experience for my children.