We've come a long way since Rachel Carson wrote 'The Silent Spring' and blew the whistle on the blanket use of DDT. That was over fifty years ago. In subsequent decades there has been polarisation and angst between farmers who embraced agrochemicals, and others who thought that they were the tools of the devil.
In the 80s, I was a horticultural advisory officer with the Ministry of Agriculture and Fisheries (now The Ministry of Primary Industries), and despaired at pig headedness in both camps. I believed, at the time, that both had knowledge to share, and looked forward to the day when the best of each would merge, and yield smarter farming.
That day has dawned. The ascendance of products and techniques for working with, rather against nature, has been dramatic. This has come as a result of good science.
As a home gardener, you can see the results on the shelves of Bunnings or Mitre 10. There you will find bug killers that you can use without worrying about killing yourself. That's because they specifically target the bad bugs, leave the good ones alone, and of course, don't affect you. I use one of these on my Helichrysum (strawflowers). Helichrysum are particularly delicious to bugs, and in the bad old days I had to don PPE, spray to kill everything, and then defer harvesting for three days. Now I can spray in jandals and immediately re-enter the block. After treatment there's still plenty of insects about, but they're ones of no consequence or some benefit.
Never have I seen such an abundance of good insects. 2022 is proving to be a vintage year for the good guys.
This autumn I've encountered more bumble bees, Monarch Butterflies, and preying mantis than ever before.
It's been five or six years since the paper wasp first decimated our monarch butterflies. I thought it was game over. But there's something different about this year. In the last month I haven't seen a paper wasp, and our self seeded swan plants have attracted Monarchs from I know not where. Perhaps the paper wasps are having their own pandemic .
Monarch Butterfly caterpillars feasting on our swan plants
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The female preying mantis has a weird habit of eating her male suiter after mating, but I can forgive her that because of all the other things she eats.
Her diet includes just about anything these plucky predators can grasp and subdue; be it the caterpillar of the white cabbage butterfly, aphids, flies, or crickets. I transferred a couple of preying mantis to a rose bush where aphids were partying. Three days later the aphids were nearly gone.
Preying Mantis checking out some Eyebright Strawflowers.
My most dramatic experience of the good insects overwhelming the bad, was the defeat of aphids in our twisted willow plantation. The invader was the giant black willow aphis, an immigrant, first spotted in Auckland in 2013.
In late summer 2017, my willows became plastered with black. That was the sooty mold which forms on the exudate of the giant willow aphid. Not only were the aphids sucking the life out of my trees, but the branches were being rendered unmarketable due to a black soot coating.
As summer turned to autumn, the infestation got worse, until finally I decided I had to do something about it. On my way to the spray shed, I detoured to have one last look at the willows. On close inspection I discovered steel blue ladybirds feasting on the aphids. They came in just the nick of time. Had I sprayed with my broad spectrum insecticide, I would have killed both the invaders and the defenders, and I would then have to spray again and again. Many branches had to be rejected that year, but since then I have had no issues with aphis in my willows.
Giant Willow Aphid
Steel Blue Ladybird
Come and check out the fat of the Monarch Butterfly caterpillars on our swan plants. Soon they'll be forming chrysalises from which more butterflies will emerge.