Do you kill spiders on sight
Builder on eight legs
From the life of the garden spider
Unlike many other species, the garden spider has a two-year rhythm of life. So there are always two differently developed generations of spiders coexisting. When the eggs are laid in September or October, there are even three generations for a few days.
Garden spider - Photo: Helge May
A few days after the eggs are laid, further development begins, so that the young spiders hatch from their egg shells before the start of the cold season. When densely packed in the soft silk fabric of the cocoon, they can withstand temperatures below minus 20 degrees Celsius.
It is March when I begin my observations of the garden spider. What I need now are cocoons with the youngest, barely developed generation of spiders. With a lot of luck I will discover two of these silk webs on an old uprooted oak. I carefully push the threads apart at one point on the cocoon. Both of them show, almost immobile, a multitude of spiders not even the size of a pinhead. In my study, I hang them up in a sheltered slatted frame covered on all sides with fly gauze, and can now follow their further development at regular intervals.
Patience in the study
At the beginning of May, everyone is still gathered in the cocoon, a large number of the spiders have already shed their skin again. Their legs seem transparent like glass, but they show increasing mobility. They left their nursery for good in mid-May. They are tightly packed together in several clumps and a few days later a large part is already on the move in a small space on their exiting threads.
Garden spider with captured buffalo chirp - Photo: Helge May
The spiders still feed on their own yolk supply, which must last until they have first acquired prey. But it won't be long in coming, because your spinning apparatus is now fully functional and at the beginning of June I find the first small, but already perfect, fishing nets. The later impressive strength of the bike nets is still lacking in the mini nets, so that even smaller houseflies cannot be held by the catch threads. The young spiders therefore mainly live on aphids at this time.
Like all arthropods, spiders have a solid exoskeleton. Only their backside is soft-skinned and can stretch a lot. Any major increase in body weight is therefore always associated with a molt. When the egg hatches, the first body shell is stripped off. The young spiders also shed their skin during their stay in the cocoon and when they have left it, they shed their old skin several times at intervals of a few weeks, up to the last, the so-called mature molt. Only then are they sexually mature.
To better observe the moulting, I get some larger spiders from the previous year. Garden spiders can be found almost everywhere, in and on buildings, in gardens, but always - and most often - outside in nature. I come back from a nocturnal excursion with several females and one male and put each one in its own plant frame. This is about 80 centimeters long, stable squared timber, at both ends of which around one meter high branches, thimble or herb stalks are attached. In between there are more stems, but only half as high. The frames are not only intended for molting, but are also intended to make it possible to observe other activities of the spiders.
Leg exercises after each moult
After a few weeks I find a female hanging upside down by a thread with her legs outstretched. Special attention is now required, because this position is considered by the orb-web spiders to be the safest sign of imminent molting. And suddenly there it is, a small crack in the old skin. On both sides of the front body directly above the roots of the four legs and slowly it continues onto the back part of the body. The old skin of the front part begins to peel off and folds up like a lid. The abdomen is pulled out of its old shell. After twenty minutes, the female has completely freed herself from her old shell and is now starting a regular exercise on her eight legs. This is vital so that the membranes between the body segments don't harden too. A steady posture while hardening the exoskeleton would lead to complete rigidity.
In late summer you can increasingly find the large, imposing orb nets of the garden spider. Garden spiders usually only set up their nets at night as they get older. Since this construction activity is an integral part of my program, I am increasingly developing into a night owl. Garden spiders are very local, because wherever the wind once carried them as a young spider, they stay - provided that the food supply is right. Over half a dozen spider spots are my constant nocturnal goals.
Precision in network construction
The new construction begins with the dismantling of the old network. Only the outer frame threads are retained. The spider usually eats the old spider silk, which - not completely digested - can be used again when building a new web later. The connection between the two plants on the side is now restored above the later network and individual threads are drawn diagonally between the outer frame system. All these threads intersect roughly in the middle. This marks the center of the later network.
Spider web - Photo: Helge May
Always starting from the center of the web, the spider now pulls around 30 spokes in different directions to the outer frame threads and attaches them to them. In doing so, she feels with her forelegs for the spokes that have already been laid, probably a kind of angle measurement that leads to this astonishing uniformity of all the spokes that have been laid. Also starting from the center of the net, a stabilizing auxiliary spiral is drawn in a few turns. This creates the basic structure in which, starting from the outside, a spinning thread evenly filled with glue droplets is drawn in as a catch spiral. The garden spider needs less than half an hour to complete this entire safety net, then it withdraws in waiting position.
Unfortunately, spiders have little sympathy, which is particularly due to their long hairy legs. But it is precisely their size that makes such a perfect, widely visible work of art possible and many of the hair and spines sitting on it are highly sensitive sensory organs that are extremely important for survival.
First wrap, then bite into it
It is true that prey is also caught at night - aphids in particular are preyed on - but the day with the infinitely flying insects brings most of the necessary food. Good for me, as I can now, after sitting many nights at night, sit in the sunlight again in front of the bicycle network. The spider sits in its hiding place. Only a foreleg is visible, which rests on a thread that leads from the net hub to its hiding place. This signal thread immediately transmits even the smallest vibrations to the spider.
Garden spider on the edge of the web - Photo: Helge May
A Schillerfly has caught itself wriggling. Despite its eight main and secondary eyes, the spider's visual sense only plays a subordinate role. Since it cannot recognize the position of the prey, it pulls the spokes with its front legs in order to determine which one is most heavily burdened by the prey. Once the catch is located, it hurries there on this spoke. After a brief touch, the garden spider sets the fly in a rapidly rotating movement with its legs, wrapping it with many threads emerging from the spinnerets at the same time. Only then does the numbing bite take place through the two jaw claws, at the ends of which there are fine openings for the poison to escape.
The now well-tied package of prey is loosened from the catching threads and dragged hanging on one of the rear legs into the middle of the net or into the hiding place. Now comes the special way of eating. The garden spider vomits some digestive juice from its intestinal tract, which pours over the fly as a small drop. After just a few seconds, it has dissolved the tissue parts of the prey that have been reached and is now immediately sucked up again as liquid food. The hook-like jaw claws literally kneaded the entire prey, so that in the end all that remained of the fly was an indefinable tangle of indigestible body parts that was simply dropped.
With the mating season, a dangerous phase of life begins for the male spider from the beginning of August. In search of sexually mature females, the males wander far and wide in the country for weeks. Before doing this, however, they store their semen in a very unusual part of the body: in the jaw probe. A small net, only a few square millimeters in size, is made on which you deposit your seed drops and pick them up again from the underside of the net with the two jaw probes.
Sexually mature females secrete an active substance, the smell of which attracts the males. However, they only detect it when it is very close to the network. On one of my outdoor nets I am lucky enough to be able to attend the advertisement until the successful mating. When the male has reached the edge of the net, a life-threatening situation arises, because the female's prey drive is often greater than his will to reproduce - and then the male is done. By rhythmically plucking the spoke threads, the male tries to attract the attention of the female sitting in the middle of the net. But at first it doesn't react. A time-consuming, cautious approach that lasts almost an hour begins. With constant tugging movements of the front legs, the male pushes himself forward inch by inch, but a sudden movement of the female causes it to rush back to the edge of the net in a flash.
Hasty semen delivery
So there is a constant change. In the meantime the female has freed herself from its position and crawls towards the male until their front legs are touching each other. It has thus announced its willingness to mate. It can be hung upside down and the male slides onto its underside. It only has a few seconds to transfer its semen, which is stored in the female's special semen pouches. Then an escape-like retreat is called for immediately, because the much larger female immediately shows the prey drive again. Even if the males can still escape their partner, they soon die a natural death. The females live a few weeks longer, because they still have to lay their eggs and ensure that their offspring can develop into a safe, protected cocoon.
Garden spider wrapped around prey - Photo: Helge May
At the beginning of October all of my "domesticated" female spiders are still hanging in their plant frames, but every night it is to be expected that they will look for hiding places. But I have taken precautions in the hope of being able to observe such a cocoon building. A larger container is available for each of the two-year-old females, lined with coarse bark and covered with fly gauze. All night long waiting begins again. In fact, it is possible to see how carefully the female prepares the future cradle. On the top of the tank, a sliver of fabric, the so-called basal plate, is created. Hanging underneath, the female spider slowly begins to turn in a circle, creating a ring wall around six millimeters high. The whole thing now looks like an upside-down bird's nest.
Exhaustion after oviposition
The egg then emerges in several spurts, with fertilization by the male sperm already present immediately beforehand. A viscous liquid surrounds the eggs, which soon dries up and holds them together. The female now covers these yellowish egg balls with a dense but airy threadwork. Finally, the entire cocoon is given an outer shell as well as fastening threads that secure it against falling or constant swinging in strong winds.
The female is now no longer recognizable: small, with a sunken, wrinkled abdomen, it is only the size of the slender male. For more than a week the female spider sits motionless next to her wood-paneled cocoon, perhaps as temporary protection or to be able to repair possible damage to the cocoon. Then suddenly she disappeared. At some point later I find it in a dark, open compartment of the desk, already completely dried out. All other of my two-year-old females have also deposited a cocoon in which the development of a new generation of garden spiders begins only a little later.
Long-term observations of native animal species are Jürgen Huhn's specialty. He has already reported on the house shrew, midwife toad, badger and dormouse for NABU magazine.
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