Michael Moreken wrote:Wow, potting soil!
I was typing in haste on my mobile so that's actually an oversimplification -- actually I have a pile of old wood chips that has composted down into good black dirt, and I was digging it out to put in my container garden containers when I encountered my first huge wire worm, almost five cm long. I was more interested in getting a photo than in grabbing hold of scary looking unknown arthropod, so it burrowed back down into the dirt in my garden container, where it presumably lived out its life cycle; I never noticed a problem.
Anyway, now that I'm back at my desk I dug up the research I did then. You are of course the best judge of what's welcome in your garden, but my own conclusion for me is that these things are as beneficial as it gets for organic gardeners, although they might be pretty rough on monocrop gardeners who spray weedkiller and insecticides.
This Virginia Cooperative Extension publication
puts it as clearly as anybody could wish:
Wireworms are omnivores, preferentially feeding on other soil insects or roots of grasses and weeds. In agricultural crops, where weeds are killed and land is cultivated, wireworms seek out the only food available, which are the underground portions of the planted crop.
That doesn't sound like my garden, which has plenty of soil insects and weed roots for the wire worms to feed on.
There's a really pretty picture of a huge wireworm very much like the one I found, at this this link.
From the various sources I was browsing during the research I did on the critters, I got the impression that they really would prefer to be forest-floor critters, with their most happiest habitat being decomposing wood like the old chip pile where I found the one shown in my photo above. That suggests to me that if a permaculture gardener was suffering wireworm damage in a particular root crop, you might be able to draw them up and out the root zone of that crop simply by mulching really well with old wood chips that are simply brimming with animal life. (My decomposed chips were utterly brimming with pill bugs, earthworms, and a zillion small insects when I was digging from that pile this spring, and that's just the macro stuff that I could see without magnification.) In other words, offer the wireworms a better deal!