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Summer insects: the night
With the common name noctu, we indicate in the garden the larvae of some lepidoptera, which we call moths (or moths), which spend their first vital stages on the foliage or between the roots of plants, of which they feed; in fact such larvae are laid by butterflies belonging to the noctuide family, but different genera of this family are harmful for cultivation, both in the garden, in the garden, and in the agricultural field. To give some examples, the Heliothis armigera larvae (also called helicoverpa armigera) feed on leaves, flowers and fruits, vegetables, ornamental plants, tobacco, corn; Mamestra brassicae loves to devour the foliage of brassicas; Agrotis segetam (and other species) prefer the roots instead, and generally they nest therefore in the ground, at the feet of the plants. The damage is generally large, but related to the number of larvae (caterpillars) on the plants; the adults overwinter in the ground, and they come out only in late spring, only in summer they become a problem, after they have laid the first hatching of eggs. A single adult of night can produce hundreds of eggs, and in one season he will lay them down three times; therefore it is important to check and limit the number of these insects before they have laid the eggs, or as soon as they have done so, before they become too numerous. Generally, in agriculture, the spread of the noctuides is monitored, using pheromone traps, to catch the adults; if the number of adults becomes excessive, the plants are treated to prevent future larvae from developing.
The terrestrial moths, also called gray worms, are very harmful, as they quickly devour the roots of the plants, causing their death; in general then we cannot see them, until they have begun to eat a good part of the root system of our plants. In addition to the roots, these nocturnal tend to prefer young plants, tender shoots, newly developed plants; they are therefore very harmful, since in a recently sown field they can quickly devour all the young seedlings that have recently sprouted. In general, the greatest damage is caused in plants and grown in pots, because insects often attack only one small plant, which therefore perishes in a few hours. In the vegetable garden and in the fields, this type of night grows with difficulty, especially when a good disinfestation of the soil is practiced, before planting the plants. Soil disinfestation is carried out using insecticide baits; but the nocturnal larvae present in the soil generally tend to prefer cultivated fields (since they need the roots to feed themselves) and a good humidity: therefore they tend not to stop in a field left free from weeds and temporarily not watered. Therefore, when at the end of winter we prepare the vegetable garden for future plants, working the soil thoroughly, and removing all weeds, we generally also limit the number of gray hilos present in the soil. If, unfortunately, we notice the presence of this type of noctuids only after they have attacked our plants, we will necessarily have to treat the soil with an insecticide for the soil, or look for the larvae and destroy them, repotting the plants.Fight the marrows that ruin the foliage
Also the adults of noctuses that have development on the aerial organs of the plants overwinter in the ground, in the form of nymphs; only in late spring does the flickering begin, and the laying of eggs on the lower pages of the leaves, or near buds and flowers. The activity of these caterpillars is mainly nocturnal, so it becomes difficult to understand what is ruining our plants. Typically they tend to cause rounded chewings on the leaves, even large ones; in addition to this, some species prefer the fruits, in which they nest, eating the pulp and depositing their excrements. In particular, some species tend to prefer particular fruits, such as tomatoes. For each fruit there is usually only one caterpillar, which also favors the development of fungal diseases: therefore, over a period of days, the fruit tends to wither and rot. Other birds instead eat buds or flowers, although the most common and common on terraces are those we can find on ornamental plants; also in this case, the damage tends to be quite serious, because even a few caterpillars on a single geranium plant can cause their death in a few days. The moths that nest in the fruits are among the most difficult to eradicate, as the fruit also acts as a nest and shelter for these caterpillars, and therefore these noctuas must be eradicated to adulthood. For the other nights, if the infestation is not serious it is sufficient to shake the plants at night, and collect the caterpillars that fall.
If instead the caterpillars are very numerous, it is necessary to carry out treatments with insecticides such as pyrethroids or with other active ingredients: in general the caterpillars are not resistant to insecticides, and therefore also a generic insecticide works. However, these products only work by contact, so we must hit the caterpillars to kill them with the product. If we have to treat potted plants, we can also use a broad-spectrum insecticide, that is to mix with the water of the watering, which will be absorbed by the green parts of the plant and will go to kill all the insects that feed on it.
Nottue: Biological control
The first action useful to eradicate the noctuids, or at least to contain the number, consists in the positioning of pheromone traps, which will catch the adult insects before they can lay eggs. In this way, of course, the lepidoptera population is essentially decimated, and the few survivors will cause significantly less damage, even producing hundreds of eggs. This type of traps must be placed in our land starting from April-May, in order to attract the first adults who come out of the ground when the heat arrives.
Another type of biological fight that is easily practiced consists in using, instead of insecticides, a product based on bacillus thuringensis, easily available on the market; this type of insecticide, completely biological, has the merit of being harmless to humans, small animals, aquatic animals, and also for useful insects, thus going to hit only the insect we want to get rid of. In contrast, most broad-spectrum insecticides, even those that are declared natural (as based on pyrethrum or pyrethroids), tend to kill all the insects they come into contact with, including for example bees and ladybirds , which we do not want to free ourselves from, as their action is of fundamental importance for the garden.