The species of spiders present in Italy are about 1.600. Among them, few are the really dangerous spiders for humans. Despite being almost all poisonousBeyond the pain that their bites cause, the effects they cause on humans are almost always limited. Except for the latrodectes tredecimguttatus and loxosceles rufescens, all the others, although they are often feared and kept at a distance (arachnophobia), in most cases are absolutely harmless.
To find out more about the spiders present in our country and to learn how to distinguish them, let's see together which are the ones that arouse the greatest interest from a medical point of view.
Black widow (latrodectes tredecimguttatus)
Il latrodectes tredecimguttatus or "Black Widow"Is the most dangerous spider among those present on the Italian territory. Also known as "malmignatta", it was so called in the early 900s, after several cases in which females devoured the male after mating were observed in captivity. Its powerful poison is neurotoxic, that is, it acts on the nervous system. The bite, immediately, is usually painless, but can have lethal effects, especially on children, the elderly or debilitated people. Several symptoms can occur within 24 hours: nausea, vomiting, abdominal pain, tachycardia or brachycardia, hypertension. In the most sensitive subjects the symptoms can be more severe, even if the fatal cases recorded remain very rare.
It is not a large spider: the male reaches a maximum of 7 millimeters, the female 15, and is quite recognizable. The abdomen, globular and black, has a series of 13 rounded red spots, hence the specific name. The spots may also be orange or yellow or not present, depending on the geographic distribution. In Italy it is mainly found in the South and Center, along the Tyrrhenian coast and in Sardinia. It lives in barren land or near walls and stones, and it can rarely build its den near the houses.
The loxosceles rufescens
Il loxosceles rufescens or "violin spider”Is also among the most dangerous. Present throughout the national territory, its powerful poison has a necrotizing effect responsible for the so-called loxoscelism. In only 40 percent of bites, this spider injects its venom, and the effects (which appear within 24-48 hours) can be variable. From a mild form with a slight symptomatology, it can get to a very rare viscero-cutaneous form, characterized by general malaise. In particularly sensitive subjects (children or immunosuppressed) it can lead to a comatose state.
The violin spider is so named because has a stain on the prosoma similar to a violin. Brown in color, it has long and thin legs, about 5 millimeters long, while the body does not exceed 9. It is a nocturnal species, which hunts without the need for a web. It weaves only a few messy threads in the narrow ravines that it uses as shelters, from which it comes out at night in search of the female. It is not aggressive and, if disturbed, tends to drift away. Precisely because it does not like the light, it can hide in clothes, in shoes, under blankets, thus increasing the chances of reacting with a bite in case it feels threatened.
Tegenaria agrestis
Il tegenaria agrentis, Also known as tegenaria of the fields, is originally from Western Europe. It has medium size: females can reach 18 millimeters in length, while males do not exceed 14. It has a rather developed back, brown in color with dark brown streaks. The abdomen, on the other hand, is yellowish. It is characterized by long legs covered with very fine brownish colored hairs. Although it prefers the countryside, it can also be found near houses, as it feeds on insects and parasites also present in the home. Its bite can be dangerous and the symptoms, although minor, are similar to those of the violin spider. Recent studies have shown that its venom produces necrotizing effects on tissues. Typically, a slow-developing lesion with extensive subcutaneous hemorrhages forms in the area affected by the bite. Fortunately, it is not lethal to humansunless there is a particular sensitivity to poison toxins. It is not aggressive, but it could become aggressive if provoked when it protects the eggs.
Florentine Segestria
One of the most spiders aggressive and from the painful bite is the Florentine segestria, present in all Italian regions. So called because the first specimens studied were found along theArno, is not considered dangerous due to its venom, with poor neurotoxic properties (it has no action on vertebrates and humans). The very painful bite is caused by large teeth, especially in females, called chelicerae, which take on an iridescent color.
It is one of the largest spider species in Europe, so much so that females can reach 2,2 centimeters in length, not counting the legs. Two peculiar characteristics of this spider are the color, typically black, and the behavior. The web it weaves has a tubular shape. Positioning itself at its extremity, it awaits its prey with six legs projected forward, ready to grab them. It can be found in cellars, crevices and old houses, especially those with uneven walls, because it is unable to climb them.
Cheiracanthium punctorium
Il cheiracanthium punctorium o spider with yellow sac, as in the case of Florentine segestria, has a poison that is not dangerous for humans. The bite, which is more painful if caused by a male, can however cause, in the most sensitive subjects, nausea, vomiting, headache, chest tightness, together with the burning of the affected area, which becomes red and swollen. Its characteristic colors are red-orange, on the cephalothorax and on the head, and yellow-amber on the back, with a transverse brown line. Larger are the females, whose dimensions vary from 10 to 20 millimeters, compared to the males, which do not exceed 14 millimeters. It can be found in meadows and uncultivated land, but also in vegetable gardens, gardens and homes. Its web, which it usually makes at a height of about 50 centimeters from the ground, has the particularity of containing one silk bag which it uses for reproductive purposes. It is present in all Italian regions, except Sicily.
Let's keep fear at bay
These are, in short, the spiders that attract the most attention. They are mostly harmless species, if the first two are excluded. Of the vast majority of spiders we encounter outdoors and in our homes, there is no reason to be afraid. Too often, these insects are killed unfairly just because they are little known, but they do no harm. Let's remember, before acting anxiously.
(Photo: Arachnophilia - Italian Association of Arachnology Facebook page)
