Hemm vanessa del cardo (vanessa cardui) huwa insett li jappartjeni għall-ordni Lepidopterafamilja nymphalidae. On some texts it is indicated with the synonym of Cynthia carduiwhile vulgarly it is also known as vanessa del artichoke, mara sabiħa u thistle butterfly. This splendid butterfly is widespread almost all over the world and is considered one of the most skilled migratory butterflies ever.
In Italy it is present everywhere, from the sea to the mountains, in the countryside and in vegetable gardens. However, its massive presence is not frowned upon in artichoke fields, due to the damage that the larvae can cause to the plants.
However, the populations of the vanessa cardui they usually remain below worrying levels. It is therefore worth knowing it and studying the incredible journeys of thousands of kilometers that it takes every year to arrive in our environments.
Description of the vanessa del thistle
This species of Vanessa has an unmistakable appearance. With a wingspan between 54 and 58 mm, it has the upper face of the wings of brown color at the root and rusty ocher with polygonal spots of black color in the median part, while in the external corner they are black with white quadrangular spots. The hind wings have a similar background color, but with dark spots near the external margin. The color of the lower face of the wings is different, tending to powder pink, with drawings similar to the upper face, but faded.
The male and female specimens of the thistle vanessa are practically identical, with the females slightly larger.
Bajd
The egg is light green in color, cylindrical in shape with depressed poles and 12-18 clear longitudinal striae. It measures approximately 2mm in length.
Larva
The young larvae of vanessa cardui they are provided with spines and have a reddish-yellow head, as well as the last segment of the abdomen. The rest of the body is yellow with black spots.
The mature larva, on the other hand, turns to a yellowish gray color, with longitudinal bands and black transverse striae. Each segment has an anterior light yellow band and bears 6 red branched conical processes with black dots. At full maturity it reaches 35-40 mm in length.
Chrysalis
The chrysalis of the thistle vanessa measures 25-28 mm in length and is brown-yellow in color with metallic reflections. We find it hanging from the natural supports upside down and tied with a silky belt.
Host plants of vanessa cardui
To understand the host plants of the thistle vanessa, it is necessary to distinguish between adult butterflies and larvae. The latter usually live at the expense of thistles, spontaneous and cultivated, such as the qaqoċċ. Occasionally they can feed on soy, tobacco, other vegetable plants such as tadam u l- brunġieltal- Boraginaceae u ta ' malvaceae.
The larvae feed on the leaf limb of the host plants, respecting only the thickest veins. On the other hand, adult butterflies, in addition to thistles, visit countless species of flowers, as they are looking for sugary substances, or nectar. So we can admire them in the gardens and in the orchards in bloom and when they feed they allow themselves to be approached and photographed easily.
The long migrations of the vanessa del thistle
Hemm vanessa cardui it is a migratory species. In Italy he spends the winter in the milder areas of the South and of the islands. Most of what we observe in spring-summer comes every year from tropical Africa and goes as far as Northern Europe. At the end of the summer it takes the opposite route: the butterflies return to Africa crossing the Sahara desert. These long migrations are usually associated with birds such as the tiblaiżda xi studji wrew how the thistle vanesse manage to complete complete migratory cycles, crossing the Sahara twice, seasonally exploiting resources and favorable climates on both sides of the desert. However, a percentage of specimens remains in the Afrotropics during the winter and its offspring are probably re-colonized in the Mediterranean in the spring.
Therefore, very long and complex journeys for these butterflies, whose population in our range varies every year according to the climatic trend during migration.
The life cycle of the thistle vanessa
In our country the vanessa del cardo completes 1 or 2 generations a year, depending on the area and the climate. The females lay eggs isolated or in pairs on the underside of the leaves. The larvae are born after a short incubation period, which averages 4 days. Once the maturity is reached in 40-45 days, the chrysalises occur which, as mentioned, remain hanging upside down on the host plants, on the trunks of the trees, on the walls or on any other support. The chrysalis stage lasts about 13-15 days. The newly released adult butterflies emit drops of blood-red liquid that eventually stain the places where they flicker. Non-migratory populations spend the winter in the adult or chrysalis state.
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