Saturday, August 3, 2013

What would you have done.....?

At this time of year juvenile spiders begin to set up their snares in our greenhouse and this one wove its fine, tent-like web across the top of an empty flower pot. They're welcome visitors and even though they are still very small they catch a lot of small insect pests - like winged aphids - that would otherwise infest the plants.

I haven't identified the species yet but it hangs underneath its silken sheet, ready to reach through with its fangs and impale anything that becomes trapped. [Thanks to Africa Gomez at BugBlog for identifying this spider as Neriene montana - there is no way I would have identified it without her expert asistance]

This morning this spider had caught larger prey - an orange ladybird Halyzia 16-guttata, which is another welcome and useful visitor. It feeds on moulds and there are plenty of those in the greenhouse.

So, what should I do? Release the struggling ladybird and, in doing so, destroy the spider's intricately woven web, or let nature take its course and watch one of these two beneficial visitors destroy the other? 

I toyed with the idea of rescuing the ladybird, but the issue quickly resolved itself because suddenly the spider let go and retreated. It may be that the ladybird's armour was too strong for its fangs, and perhaps its captured prey emitted some deterrent - other ladybirds, like the six-spot, secrete a noxious fluid it they are attacked. 

But would the ladybird then remain entangled in the web and simply die of starvation if I didn't rescue it?

As it turned out, no. It simply walked around on the finely woven surface of the web until it found an exit and then flew away.

It often seems that much of what we humans do under the banner of 'conservation' should really be called 'conscience-driven intervention'. We intervene to alter checks and balances between species, often using criteria that have little to do with science but have more to do with sentiment, Sunday school notions of 'good' and 'bad' in nature and that widespread fantasy called the balance of nature. Maybe sometimes it's better to just stand and watch.