What is the use of the common knot wasp? – The green Amsterdammer

A common knot wasp (Cerceris arenaria) tries to paralyze a striped weevil (Otiorhynchus sulcatus) with a sting

© Rob Company

Every year in my area a wonderful tragedy takes place. During the summer months, hundreds of common knot wasps (Cerceris arenaria) active. The females of these wasps dig underground breeding cells, which they fill with food for their larvae. The food? Live weevils, paralyzed after a sting in the soft tissue.

When it comes to insects like common knot wasps, we regularly hear: ‘What is the use of these insects?’ In fact, anyone who types the phrase “what’s the use” into Google will see it automatically completed with words like “mosquitoes”, “ants”, “wasps”. But understanding the value of insects in terms of utility reveals a poor view of the rich world we live in. Moreover, this view does not prevent the decline of insects labeled as useless.

The question of the usefulness of insects is not an isolated issue. It expresses a strong feature of our society. We – myself included – have a strong tendency to reduce the value of things to their usefulness, to their instrumental valuewhat they contribute to something else. According to this school of thought, literature is valuable in so far as it stimulates our empathy, science in so far as it enables us to solve pressing (and less pressing) social problems, religion in so far as it gives people peace of mind whether or not they is on his deathbed or not. , etc. The list has no end.

Everything seems to be subject to this instrumentalizing logic, even the most fundamental aspects of our lives. The value of a relationship can be reduced to its ability to remove loneliness, to have children pass on genes, and even the value of our life can be reduced to the answer to the question: will it please me? the next life?

This way of thinking leads us to lose sight of the problem itself and focus only on its (beneficial or not) effects. We see not a literary quality, but a possibly stimulated empathy, not a curiosity and wonder-driven research, but an opportunity to solve social problems, not the meaning of participation in religious practices, but effects on mental health.

A jewel wasp watches the burrow of a common button wasp from a blade of grass

© Rob Company

Don’t get me wrong: having an eye for utility is not necessarily wrong, and in some cases it is extraordinarily sensible. However, when value is understood only in terms of utility, it leads to enormous impoverishment. And I don’t think anyone needs to be convinced of that. In everyone’s life there are things that resist utility. We all know ourselves trapped by things that we value for their own sake: whether literature, science, religion, our spouse, our children, our very existence, or something else entirely. If someone were to ask us what its use is, we would feel that we have to speak a language that does not do it justice. People interested in literature shy away from talking about the usefulness of literature, and parents do not talk about their children in relation to the usefulness they bring.

Nevertheless, when we are asked about the usefulness of the things that have seized us, the temptation to answer in terms of usefulness is very great. For example, those who love nature often talk about the benefits of forests and bees, worms and wolves. Forests are valuable because they store CO2, bees are important pollinators, worms are useful in improving soil quality, and wolf advocates point to its role in keeping deer, red deer and wild boar populations healthy. How is it that these considerations are so influential? Much of our nature is under pressure, and pointing out its usefulness is probably the most effective weapon one can use to protect it. It is often thought that a person who cannot convince nature’s opinion of its intrinsic value is a hopeless task, but no one can deny that nature is useful.

When someone asks me about the usefulness of common knot wasps, it is also tempting to refer to their instrumental value. I could truthfully say, “The common knot wasp is a natural control agent against weevils, a group of insects known to damage crops grown by humans.” There is a good chance that this ends the question for the asker. After all, I would have legitimized the existence of the common knot wasp by pointing out its usefulness. The fact that it also has a positive effect on a human project (agriculture) probably makes that legitimacy even stronger emotionally.

This reflex—wrapping perceived intrinsic value in considerations of utility—is quite understandable. Still, I hesitate to speak this way. First, the instrumental value of common knot wasps is relatively small. Only a small proportion of the weevils fall victim to them. In addition, it is quite conceivable that humans will find a better way to control weevils in the near future. Resources are almost always interchangeable. If the value of common knot wasps can be reduced to their contribution to the control of weevils, and humans have found a better way to do it, then the disappearance of this beautiful species of wasp would mean no real loss.

Second, I would think I had committed treason. After all, by talking only about the role of the common knot wasp in the fight against weevils, I completely ignore these fascinating creatures themselves, of their complex beauty and beautiful complexity. Just as lovers of literature and parents shrink from speaking of literary works and children in terms of their utility, so I hesitate to speak of nature in general, and insects in particular, by reference to their utility.

A common knot wasp rests in the opening of its nest

© Rob Company

Is there another possible answer to the question of the usefulness of insects? Yes, and it consists in putting aside our interest-influenced gaze and really seeing the world outside ourselves. Philosopher Iris Murdoch (1919-1999) described this ability as loving attention. Paying attention is incredibly difficult because the ego repeatedly threatens to cloud our vision with its interests. But to the extent that we manage to pay attention, we notice and marvel at ‘the great, surprising diversity of the world’.1

Last summer – knees in the sand, camera in hand – I was captivated by the fascinating lifestyle of the female common knot wasp. Darker than the well-known ‘sap wasp’ and between 11 and 16mm in size, these creatures, common in the Netherlands, have long, strong hairs on their front legs. This enables them to dig their nests (tunnels that open into several underground breeding cells) in warm, dry places with open sand.

They fill it – I already wrote it – with weevils. One summer morning I witnessed the hunt. A common knot wasp female found a striped weevil (Otiorhynchus sulcatus), surprised him, grabbed him with paws and jaws and tried to paralyze him with her sting. It was not easy, as weevils have a hard shell. She therefore tried to put him between the stomach shield and his head – in the neck, as it were. But to do that, she first had to turn the beetle on its back or side. It was a gruesome and at the same time immensely captivating spectacle that took place in a messy corner of an ordinary backyard.

When the weevil is paralyzed, she tries to take him to her nest. But it’s not easy either, as the beetle is smooth and not much smaller than itself. She therefore uses her jaws to hold one of its paws. She clings to his body with her paws and then flies, heavily laden, back to her nest. This nest is often near dozens or hundreds of other nests. If you take the time to look at the nests, you will constantly see females arriving with exchanged weevils and will be impressed by the challenges they face. For example, she has to find her own nest entrance in the middle of all the other tunnels. She probably succeeds because she is able to visually characterize the immediate surroundings of her nest. And then there are the males who, near her nest, are out to mate with her. I have regularly seen her attacked while she has her hands full with a paralyzed weevil. Because she is bigger and stronger than the males, she usually succeeds in chasing them away.

A common knot wasp flies towards its nest with a striped weevil

© Rob Company

When she goes hunting, she leaves the nest entrance open. As a result, she is able to pull in the captured weevils immediately upon arrival. But it also poses a serious problem: parasites that target her eggs, larvae or the captured weevils. When she is absent, nothing prevents them from entering the nest and laying their eggs in the brood cells. Soon after I came across a place where the common knot wasp is abundant, I saw small, red-green-blue shiny wasps crawling around. They turned out to be jewel wasps (Hedychrum noble). When the jewel wasps think the coast is clear, they sneak in, lay an egg in a brood cell and run for it. When the egg hatches, the jewel wasp larva kills the common knot wasp larva(s) and has the supply of weevils for itself.2

If her nest is not parasitized, then her larvae have the still alive but paralyzed weevils at their disposal. They eat it bit by bit until they are fully grown themselves. They grow in a protected underground environment and, after undergoing a complete metamorphosis, emerge as adult wasps a year later.3

This is only part of the story of one species of burrowing wasp. There are more than 160 species of digger wasps in the Netherlands, even less than half of the more than 400 species of wasps in our country. They all have their own story. How wrong is the idea, often heard, that there is no longer any nature in the Netherlands.

The Dutch philosopher Cornelis Verhoeven (1928-2001) writes in just looking that as soon as we are really aware of something, an “incurable wonder” arises within us. That’s exactly how it is. When we see the beauty and complexity of an insect like the common knot wasp, we begin to wonder. We become ‘amazed witnesses’ to a world that we realize is much richer than we thought. The question of utility disappears, that question now turns out to be hopelessly trivial.

Rob Compaijen is a postdoc at the Protestant Theological University (Amsterdam), where he researches the role of detachment in ethics. He is also writing a book about envy.

Leave a Comment