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Gardening

Lepidoptera


General informations


Lepidoptera are an order of insects from about 160,000 species, more commonly known as butterflies and moths. Most of the known species belong to the suborder of the Glossata. The name "lepidoptera" derives from the union of the Greek words "scaglia" and "ala", with reference to the scales, arranged like the tiles of a roof, which cover the wings. It is these scales that, together with numerous chemical pigments, give the variegated colors to the adult moth specimens. Lepidoptera can be of different sizes: the largest butterflies are found in tropical areas, but in Mediterranean countries they are smaller in size. Lepidoptera move in flight, going from very short journeys for some species to real migrations for others, up to 2500 km. These insects generally escape predators thanks to their colors which allow them to camouflage or which vividly warn other animals of the presence of toxic or repellent substances, sometimes accompanied by particular sounds and smells.

Biological cycle



The biological cycle of lepidoptera is composed of four stages: egg, caterpillar, pupa and adult form. In each stage, shape and eating habits change considerably (metamorphosis). The eggs are laid on the leaves, where they hatch and the larvae or caterpillars come out. The caterpillars are elongated cylindrical in shape and blend well with the foliage; they can have bristles and move with three pairs of thoracic legs and with abdominal pseudozamps. They have a powerful chewing apparatus and feed on leaves and wood. Once mature, the larvae are incrisalidated inside a cocoon or remain anchored to a substrate by a silk support: it is the moment in which they become pupa. The butterfly will come out of the lining of the pupa (flicker), which in turn will give life to another biological cycle by laying new eggs. Lepidoptera biological cycles generally vary from two to four each year.

Morphological characteristics



Lepidoptera in their adult form have a distinct body on the head, abdomen and chest; wings and legs are appendages of the chest. Each moth has two pairs of wings and generally the front ones are larger than the rear ones. Lepidoptera wings are membranous and are crossed by nerve fibers and small tubes that carry oxygen. On the head, of small dimensions, are placed compound eyes, formed by hundreds of small lenses. Sometimes even simple eyes, called ocelli, are present. The antennas are placed between the eyes, fundamental as they are organs of chemical and tactile sense. Most moths feed on sugary liquids such as nectar through a spirotrumpet, a sort of proboscis that is coiled at rest under the head. The spirotrumpet can also reach triple dimensions with respect to the body of the butterfly, allowing it to feed itself by vibrating in flight over the flower. Butterflies lacking a trumpet are fed with pollen.

Lepidoptera: Damage caused



The adult moths are harmless for plants, but at the larval stage they are voracious devourers of leaves. The caterpillars are divided into three categories: miners caterpillars, which dig tunnels in the leaves and in the wood; defoliators caterpillars, which leave only the ribbing of the leaf; embroidering caterpillars, which leave an embroidery on the patina of the leaf on which they feed. To eradicate this pest it is important to eliminate the eggs from the plants immediately. If the infestation is extended but it is necessary to resort to chemical or natural insecticides. Chemical remedies should be used only if the infestations are of serious entity, given their negative impact on the ecosystem. There are now numerous natural remedies that are effective against caterpillars, such as the pyrethrum and the bacillus thuringiensis. Pyrethrum is a substance extracted from flowers, which has the disadvantage of eradicating both harmful and useful insects. Bacillus thuringiensis is a bacterium present in the soil that neutralizes larvae.