The fasciated sword can be recognized among a thousand with its stripes black and yellow. Upside down, the spider waits patiently for prey to wash up in its web. Zoom on an invertebrate in the body of de wasp.
The fascinated sword, like a wingless hornet
Very common in southern Europe and northern Africa, the Eurasian Spike (Argiope bruennichi) belongs to the family of Araneids. It is also called, argiope fasciated, argiope striped or argiope hornet in reference to her striped dress which looks like that of the big wasp. Like all spiders, the Eurasian Argiope has eight legs, is devoid of wings and antennae. At the front of the body, its pedipalps are used to catch and handle prey. Smaller and closer to the mouth, the chelicerae are appendages with hooks that inject a paralyzing venom. Almost blinded and deaf, the spider has developed the senses of taste and touch.
A very marked sexual dimorphism
The body of the fasciated spider divides into two parts : in the front, a downy cephalothorax (the prosome) is adorned with silvery gray and in the rear, a globular abdomen (the opisthosome) displays yellow and black stripes. The individuals are more or less contrasted or dark. It is reported that the black and yellow bands allow it to stand camouflage facing its predators (birds, lizards…). The species exhibits sexual dimorphism pronounced, quite common in spiders: the female is between 10 and 22 mm long and the male between 4 and 8 mm. This one displays other differences :
- His abdomen takes on a more elongated shape;
- Its colors are duller and its abdominal patterns diffuse;
- Its first two pairs of front legs are slender and long.
Open places for the fasciated sword
This species native to the Mediterranean area is found from North Africa to European continent where it is widely distributed: from Scandinavia to Spain via Central Europe. In these regions, she frequents circles open, sunny and dry, in the tall grass. It also wanders in wet areas, near ponds where potential prey swarms. The presence ofman does not particularly frighten it and it appears in ditches, roadsides, wasteland, parks, meadows and gardens. It is observed mainly from July to October.
Circular canvas for the fasciated sword
The hornet argiope is a spider orbital (from the Latin orbis, circle, and tela, web) which means that it makes a circular web. Still there upside down, she takes advantage of dawn or dusk to make her work less than a meter above the ground in low vegetation and tall grass. The silk comes out of the dies placed at the end of the abdomen in the form of a paste immediately stretched by the legs to form the threads. The elaboration of its large and round canvas takes about an hour and is distinguished by a zigzag called “stabilimentum” characteristic of the epeire and which stabilizes it. The fascial aargiope usually stands in its center, with the legs spread two by two, forming a sort of cross. Its typical position earned it the English vernacular name of cross-spider.
Big prey for the hornet argiope
Given its size, the Eurasian Spike can attack large insects: locusts, grasshoppers, wasps, bees, hornets, dragonflies, cicadas, butterflies … When an insect sticks into the web, the spider melts on it, immobilizes it with a paralyzing venom inoculated through its hooks. The striped argiope will then tie its victim with silk, deteriorating part of its web that it will rebuild after its meal. Like other spiders, it digests the liquefied flesh of its prey thanks to digestive juices that she regurgitates. When its booty is tiny, the argiopus kills it and immediately consumes it without surrounding it with threads. In other cases, she can keep her alive as Reserve of food.
The sexual cannibalism of the fasciated sword
Mating is usually done in fine weather, after the month of March. The male, much smaller than the female, must be very careful during courtship display. During his attempts to approach, he surrounds the legs of his partner with silk thread then tries to introduce his copulatory bulbs into the epigyne of the female. At the end of the mating, he will abandon his copulatory apparatus in order to decrease the chances of a rival to impregnate his bride and to increase his chances of survival. Indeed, if he does not flee as quickly as possible, he risks being immediately devoured by his partner.
Cozy cocoon for young argiopes
The spermatophores that the female has collected allow her to fertilize several eggs. About a week after mating, she will lay 200-300 eggs in a cocoon made up of several successive layers of brown silk providing thermal insulation and impermeability fireplace. If the eggs hatch very quickly, the larvae will spend the winter protected from frost in the cocoon only to come out spring following. In fine weather, after their first moult, the young spiders climb to the top of a twig and throw a thread that carries them into the tunes. This is how they earn their independence.
The Short Life of the Fascinated Sword
The threats weighing on the Barred Argiopus are linked to the reduction in the number of its prey due in particular to insecticides and frequent mowing. It is itself directly poisoned by the massive use of pesticides in crops. Fasciae is also a victim of Tromatobia ornata, a predatory insect which lays in its cocoons. The larvae of this parasite will then devour the spider’s eggs. With regard to its diet, the hornet argiope does not cause any damage in the garden and shows itself completely harmless towards humans. The sword only livesa year and dies before the first cold.