A brief post this week on the bugs and the bees – well actually, mostly bugs. In fact, not really bugs either, strictly defined. Hell, I’ll just get on with it.
Like most growers, I keep a keen eye out for certain insect pests that tend to plague the crops at predictable times of the year, like flea beetle, carrot fly, aphids and cabbage whites. But I’ve also noticed over the years cycles of various other insects and invertebrates that don’t impinge so directly on the crops.
Early in the spring, the garden beds are rife with small wolf spiders (useful little critters) and the air is filled – briefly – with hawthorn flies (aka Bibio marci, named after St Mark’s day when the adults emerge – apparently they’re potentially useful pollinators). Later in the summer it’s the turn of the cardinal beetles, Pyrochroa serraticornis – predators of flying insects, so also potentially useful. And pretty little things to boot, as you can see.
In the autumn, the orb web spiders seem to come to the fore – or is it just that their webs are more noticeable in the dewy mornings? Voraciously insectivorous things – how useful!
This autumn I’ve also witnessed huge numbers of crane flies (Tipulidae spp), whose larvae – leatherjackets – eat crop roots, so definitely not useful. And then just recently as the crane flies have dropped off, a plethora of harvestmen – also generally insectivorous, and therefore useful.
Whether these species consider me to be useful in turn is something I have been unable to ascertain, although I suspect that the leatherjackets are keen followers of my horticultural activities.
This year there were far fewer hawthorn flies around than usual, but far more crane flies and harvestmen, which I hadn’t noticed en masse previously. Presumably, most of them only make themselves noticeable to me when they’re putting themselves about in the mating season – that’s certainly the case with the hawthorn flies, but I’m not so sure about the others. Amazing really how little most of us know about the things going on under our noses.
Having observed our Vallis Veg site (albeit not very systematically or actively) over the past ten years, it does seem to me that it’s getting more insect-rich as we’ve diversified it and indeed left quite large parts of it pretty much alone – on a hot summer’s day there’s certainly an audible buzz as you enter the site that you just don’t hear in the surrounding fields of arable and ryegrass. Of course, there are extensive ecological debates about this sort of thing, including the so-called ‘land sparing vs land sharing debate’ which until recently seemed to come down against the view that any kind of farmland was of much ecological use, fuelling the notion that we need intensive industrial arable farming and then as much undisturbed wilderness as possible. Quite why people think that intensive industrial arable ‘spares’ land is beyond me, particularly when about 40% of the calories it produces go for stock feed and biofuels – but it doesn’t stop the New Scientist printing pictures of giant American combine harvesters under headlines stating that this is the greenest way to farm. Anyway, some recent research suggests that agro-ecosystems may not be so ecologically useless after all. The studies referred to tropical agroforestry systems, but I wonder if it may also prove to be true of temperate mixed farming or agroecology. Not really, according to an interesting talk I attended by David Bohan: small islands of biodiversity in a sea of monoculture have no effect (though it may be otherwise if everyone started farming agroecologically).
Ah well, what do I know, I’m just a bloody peasant (…on which topic, more soon). Objections to our recent planning application included the comments that our activities had made the site both unkempt and bad for wildlife. But I kinda like our mix of hedgerows, trees, wild tussocky grass, weeds and the odd kempt bit. And, though I can’t really tell, I think the wildlife does too.