Getting Rid of Bugs

I have difficulty with insects and other critters eating the plants I grow. Greenpa doesn’t use any pesticides or herbicides on his crops and my mum tells me to just grow more than I need and then I can share with the critters, but I don’t have much room. So I try to kill the bugs without too many toxic chemicals.

marigolds in the vegie garden at the local school I like the idea of companion planting and I have a book called Companion Planting by Brenda Little (Reed, 1982). I’ve heard that it isn’t scientifically proven, but the book is so pretty that I do what it says. Maybe if I believe enough it’ll work. One thing the book says is plant marigolds with everything, so I do. The school near my house has a vegetable garden and they have marigolds in all the beds so it’s not just me. The flowers look so pretty among the green vegetable plants.

basil, tomatoes and marigolds at the end of summer Many herbs ward off problem insects, so planting in amongst vegetables is a good idea. And rows of the same plant (monoculture) are an invitation to pests. Mixing up different plants alleviates this problem. I always plant carrots with onions, peas with mint, basil with tomatoes and beans.

Wormwood is meant to keep cabbage white butterflies (Pieris rapae) away, although I’ve seen them flying near my wormwood plant. But it’s probably the caterpillars it kills, because I’ve been told to soak the leaves in water and spray this on cabbages. I don’t do this because I never grow cabbages. My dad has grown cabbages and you would come across slugs as you chopped them, which I didn’t like. Wormwood is pretty harsh because it’s an ingredient in absinthe. I once dreamed of growing lots of wormwood and making my own absinthe, but I think you have to do a bit more than just soak the leaves in water.

Of course there are lots of beneficial insects, like bees and lady-birds (ladybugs, lady beetles). And spiders are every gardener’s friend. The Department of Entomology at Texas A&M University has a Plant Pest Identification Aid which includes Beneficial Insects and Spiders. It’s North American, but the vegetables I grow are introduced species and so many of the pests are too.

I found tiny grey bugs (which I think were cabbage aphids) on the bok choy. I thought spraying vinegar on the leaves might help, but I didn’t have a sprayer, so I diluted it in water and poured it on. That didn’t work and my dad suggested pouring detergent on them. I run the grey water from clothes washing onto my garden and so the next time I washed, I poured some of this grey water on the leaves with the mites. That got rid of them. The Virginia Tech link above says the organic control is to spray foliage with insecticidal soap, so I guess I made my own.

This winter my peas had 1cm long furry black caterpillars. In the past I’ve used Bt (Bacillus thuringiensis) to kill them. Bt occurs naturally in soil and is an acceptable natural pest control, widely used in organic farming. The commercial preparation is made of dead bacteria and sprayed on the leaves of the plant.

When the insect [pest] eats the dead bacterium, the toxin is partially digested in the insect gut by proteolytic (cutting) enzymes and converted to active Bt toxin…The actual bacterium, which is not eaten by any insects, degrades in the light/sun/rain pretty fast (less than a day).

A number of crops have been genetically modified to express the Bt toxin and this is not a natural pest control. In this case the active toxin is in every cell of the plant and cannot be removed before people eat it. There has been some research that suggests Monarch butterflies (Danaus plexippus) are killed by Bt corn.

The Bt I used didn’t work (my dad later told me it might have washed off too soon) so I tried Derris Dust. It’s made from the powdered root of Derris eliptica. I didn’t powder the root myself; I borrowed a bottle of it from my dad. The label says it’s not harmful to plants, animals (apart from caterpillars and aphids) or humans, but it does kill goldfish.

cabbage leaf eaten by snails Ducks eat snails. I really want to get ducks, but I don’t have room in my current garden and my cats would stalk them (although maybe not kill a duck their own size). I use snail bait, because I’m the lazyst gardener (too lazy to walk around in the morning picking off the snails and drowning them in beer) and the snails eat all my seedlings, and everything else. The other day I found out that bob-tail lizards eat snails and if the snails have been poisoned the lizard will die. The Blue-tongued Lizards at this link are from New South Wales, but this picture of a Shingleback or Stumpy-tailed Lizard (Tiliqua rugosa) looks just like the bob-tail lizards (with blue tongues) that live in my area. And yes they open their mouth wide to scare you when they get scared.
Shingleback or Stumpy-tailed Lizard (Tiliqua rugosa) by E.Cameron

Adult blue-tongues adapt well to suburbs where there are large backyards with plenty of shelter. They rapidly become used to human activity, and may live in the same place for many years. Rockeries, horizontal pipes and the cavities under houses are favourite hiding places; sunny paths and lawns provide basking sites. Plenty of food such as snails, slugs and caterpillars is usually available in gardens, and a blue-tongue in the garden will help to keep down the number of snails and plant-eating insects. Unfortunately, blue-tongues will also eat snails and slugs poisoned by snail baits and can be poisoned themselves.

The summer before last a bob-tail installed himself in my garden. I have strawberry plants and this was what he wanted (not the snails). I didn’t mind sharing with him. Last summer I only saw him once. Unfortunately Sheeba the dog stood next to him and barked until I went to investigate. She may have scared him away, because I didn’t see him again. But my strawberries weren’t as productive, so I’m hopeful he’ll come back another time. After finding out about the snail eating, I wonder if I killed him. And he would have eaten all the bugs!

As well as poison and angry dogs to contend with, bob-tails often get run over by cars. The hot road is too tempting a place to warm their blood in the morning.


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