A hissing beetle

I was surprised and, to tell the truth, a little unnerved by the loud hissing sound generated by the small black beetle that I had just picked up. It was as if there was some kind of deep-rooted instinct to pull back from any creature that hisses at you; some evolutionary impulse, derived from ancestors exposed to the harsh realities of living alongside more dangerous animals than this small beetle. I knew what the beetle was, knew that it was harmless and yet I felt a momentary flash of fear. Why was this? That such a reaction was provoked, despite my knowledge of this beetle, might seem to suggest that this irrational response is inherited and not simply a behaviour learnt during childhood – nature winning out over nurture. However, things are not as clear-cut as this. Experiments using young, wild-born monkeys suggest that a fear of snakes is learned by watching how other group and family members react. A monkey that is shown a video of another monkey reacting to a snake, learns to fear snakes itself but, manipulate the video to replace the snake used in the experiment with a flower and a naïve monkey (that has never seen a flower) does not suddenly learn to fear flowers. This, and similar experiments, demonstrate that monkeys learn to fear some objects (e.g. snakes, spiders and water) more readily than they learn to fear other, typically less threatening, objects. So, there may well be a genetic influence at work here as well.

The beetle in question goes by the name of Cychrus caraboides – it has no English name and specialises in feeding upon snails. The hissing sound, subtle though it is, is presumably a measure deployed to warn off potential predators. A similar approach is adopted by a wide range of other insects and, indeed, by a number of vertebrates. Great tits, for example, will hiss if disturbed on their nest and it has been suggested that these birds, and a number of other cavity-nesting species, hiss to give the impression to a potential predator that there is a snake in the cavity and not just a defenceless feathered meal. In other species, notably snakes, the hissing is a warning which is backed up by a venomous bite. Because of this, and because of the underlying threat implied by the act of hissing, other, harmless, creatures have been able to use hissing as a form of deception – making out that they are dangerous when in fact they are not. Although I had nothing to fear from this beetle, I must admit to holding on to it for a rather shorter time than I would otherwise have done!