I thought you might like to see a really ucky picture of aphid infestation on a stem of Russian kale. I’ll pull it out in a few weeks’ time, but for the moment why am I leaving it?
My guess is that for some of you the very thought of leaving such an ugly shoot in the garden would cause you to cancel your subscription to this blog and erase me from your twitter list. But please don’t do that! Let me tell you why this is good.
Firstly let’s talk about the aphids.
Aphids are Species Specific
You need to know that aphids don’t cross from species to species. The aphids infecting my kale are Russian Kale aphids. They won’t bother the lettuces or the tomatoes. If you look closely you will see that they have evolved in just the right shade of reddish green to disguise themselves perfectly.
Aphids are food for ladybird larvae
The seven spotted ladybird can eat 5,000 aphids during its life span. If you don’t have aphids in your garden you won’t have ladybirds.
Parasitic wasps use aphids to hatch their eggs
These wasps, which are solitary and good pollinators, lay their eggs in aphid carcasses. If you've ever seen the white carcasses on foliage, you can bet that the wasps have been incubating here.
Don’t spray the aphids, you’ll kill the good guys too
Some people might turn to the pest spray, but they’d be doing themselves and their gardens a bad turn. If I were to kill aphids on sacrificial plants like these, I would also be killing the young ladybirds and wasp hatcheries that use them. I would reduce the potential for ladybirds to control pests elsewhere in my garden. I’d also be reducing the population of pollinators, not only killing the wasps, but bees, hover flies and other beneficial insects that make a massive difference in the harvest I will get from crops like beans and peas.
Preserve the bottom on the food chain and the top will prosper too
Ladybirds eat aphids, spiders eat ladybirds, flies eat spiders, birds eat flies and birds eat slugs. If I can encourage the natural hierarchy of insects into the garden birds will follow. As I write this a Robin is rooting about in the undergrowth. This new visitor is a first for the rooftopvegplot, six stories up in Central London. I directly attribute the Robin to my organic gardening methods, and my laxness with aphids.
But if all that wasn't good enough, leaving the Russian Kale has brought other benefits. The bright yellow flowers and lush foliage look wonderful in early spring, when the vegplot tends to be a little bare. And all those early flowers provide high grade pollen for the solitary bees and wasps that I’m busy trying to attract to the garden. This is a real symbiosis between humans, plants and insects that I love to be a part of.