When I returned to Yew View after the first lock-down, I must admit I was not very pleased to see a huge hornet nest in our tawny box. This box has been used for the last three years by our resident Tawny pair and I have invested a lot of time in perfecting three cameras and lighting to film the story of these amazing birds of prey.
The nest was already pretty huge, obscuring the views from both cameras. We could see the hornets in and out continually, so there was nothing we could do but wait until the nest died off naturally. These are only used for one season and as we near winter and temperatures drop and the life cycle of the nest ends, these nests can safely be removed.
When we say 'hornet' most of us imagine a very large and viscous wasp-like creature. In fact, European hornets are not aggressive. Outside of the nest area hornets never attack without good reason. Hornets are amazingly peaceful which prefer to evade conflict. Scientifically it has been shown that stings of hornets are not more dangerous than bees and wasps. It is their considerable size (queen to 35mm) and loud flight noises that induce most fears. As with most flying insects, it is the panicked arm thrashing that often induces a sting.
I had been watching the nest both from the outside and via the cameras inside. With the tawnies now prospecting for nesting spaces, I was keen to get it out as soon as possible. I could not see any hornet activity, so I decided it was safe to go up and take a closer look. Climbing the ladder, I gently knocked the box with a stick and waited to see if there was any activity. Nothing. I gently started lifting the lid, slowly, pausing to see if there was any reaction. Still nothing. I removed the lid to reveal a truly incredible sight!
There was no visible activity in the nest, so taking a knife, I gently removed the nest from the box interior and carried it down the ladder. It was HUGE!
Laying it gently on the ground, I was able to look more closely at this miracle of insect architecture....
As the back section had been up against the side of the nest box, it was open and revealed the incredible chambered structure inside. The different 'storeys' were clear, each full of hexagonal chambers, where the larvae had grown. There were a few dead larvae in some of the chambers and two very sluggish hornets, near the end of their life.
The nest is created by the hornets collecting scraping slithers of wood from trees, fences and other wooden structures. Mixed with saliva, it is applied and shaped. It just blows my mind how they create such an intricate structure with such precision! I just could not stop looking at this miracle.....
On trying to find out more about the hornet life cycle and a bit more about their nests, I was dismayed to find that 90 % of the content online was about removal and destruction of the nests, which I felt was a great shame.
One site, I did find, helped me understand more about what happens in the life cycle of these insects. I have based this text on that site. (http://www.vespa-crabro.com/hornets2.htm )
The queen starts by deciding on a nesting-place, where she first makes a small pedicel (stalk) from which the nest will be suspended. The first cell are built outwardly from it and are soon all occupied with eggs. After five to eight days small larva (quantity 1-2mm) develop, which during the coming twelve to fourteen days pass through five larval stages. When fully grown the larva produce a fine silk thread, from a special gland, to cover the cell, like a cocoon. Protected within this, the first hornet pupae metamorphose during the coming thirteen to fifteen days.
Workers will stay in the nest for two to three days before taking their first flight. Around this time a paper sleeve is started, which will eventually cover and protect the cells. Each worker cell can be reused up to four times.
After five to ten female workers have emerged, the queen starts to fly from the nest less and less, with the workers taking over the role of foraging. Workers are noticeably smaller (18-25mm) than the queen (35mm), and only live for three to four weeks. Eventually the queen becomes nest bound and will never leave the nest again. With queen safely hidden in the nest, the most dangerous time for the colony has now passed. The queen now focuses solely on reproduction, the function she will perform until her demise at the end of the season.
After completing the first comb a new pedicel is built to allow construction of a new tier. Construction occurs basically downwards from the first comb, with additional lateral expansion of each comb and the paper.
Hornets and other social wasps use paper (wood pulp) to construct their nests. In other words: they use rotten wood as the main building material for the nest. They scrape it from worn and weathered wooden fences, buildings, telephone poles, and other sources. They mix this with saliva and chew it up into a ball with their mandibles (mouth parts). This softens the wood fibre. After a period of chewing, the hornet adds the paste to the nest structure and spreads it out with her mandibles and legs. After it thoroughly dries; a type of tough, durable paper is formed. The stripy pattern produced on the comb is characteristic of the hornet, each different coloured stripe representing the pulp from a different tree.
Larvae are nourished by the adults with this mixture of captured insects, paralysed and masticated, which they regurgitate.
In the time between mid August and mid September, the hornet colony achieves its developmental peak, amounting to 400 - 700 insects and a 60 cm high nest. The queen now lays eggs, which become males (also called drones, quantity 21-28mm) and young queens.
The appearance of the first sexuals (queens and males) indicates the decline of the colony. The workers gradually neglect the old queen and she eventually leaves the nest and, exhausted from oviposition, dies.
The workers are now busy feeding the sexuals with protein and carbohydrates. This provides the young queens with the necessary reserves for the long hibernation phase.
The sexuals do not take part in the work, just sit on the comb and feed. At this stage unemerged larvae have no chance to develop and lose weight eventually falling from their cells.They collect by trees or close to the nest. After mating, males die quickly.
The inseminated young queens now hunt for a suitable hibernation place. With a short life span, the last female workers die at the beginning of November and with them the last activity in the nest.
Old nests are never used again the following year. Many young hornet-queens do not make it through the winter falling victim to fungal attack or predation by insectivores.
A fascinating insight into an insect that I knew very little about.....
I have popped the nest in a large box, in a cold outhouse, just to ensure there are no hornets still in there, before I take it into school to show the pupils at the school I teach at.
With the tawny box clear, it was time to clean it out. At the base of the box was a lot of debris from the nest; dead individuals and the dead larvae which were beginning to rot. A lot of flies had been attracted to this and I must admit, it did not smell good! With gloves and a trowel, I cleared all the debris from the bottom of the box and replaced it with a deep bed of fresh rough wood chippings, leaves and garden wood debris.
Luckily, neither of the camera lenses had been damaged and I was able to clean them off, ensuring the views inside the box were reinstated.
The view from this box is pretty special....
As you will see from my other recent blog posts, we have other owl boxes on site and the pair have been showing a lot of interest in a box near the river. I wonder if they will come back and have a look at the box again that they have bred in for the last three year? Here are a couple of clips of previous breeding successes..
You can see why I want to get this box sorted..... it is a highlight of all my wildlife year! You can see other clips from this box, and more, on my Yew View YouTube account