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Mealybugs are rincoti, like aphids; these insects pierce the leaf blade or young stems and feed on the sap contained in them, rich in sugars. The parasites commonly called cochineal are many, a few dozen, of various sizes, from a few millimeters, to half a centimeter or more. They generally colonize young parts of plants, buds and leaves in large numbers; There are also species that infest the roots, causing serious damage to plants. The male specimens are provided with wings, while the females lack them, sometimes after laying their eggs they also lose their legs, becoming in practice protective containers for the new generation. The mealybugs they are easily recognizable from other insects because they tend to be covered with waxy protective substances, forming a hood in the shape of a small shield, rigid or rubbery depending on the species. Between mealybugs more widespread we remember Iceria, Saissetia (with rigid external shield, often dark in color), Ceroplastes (with adult forms covered by a waxy shield), Chloropulvinaria (or cochineal fioccosa), Pseudococcus and planococcus (mealybug).
Mealybugs spread over conifers, succulents in general, many ornamental plants, vines and citrus fruits; they develop best in the cracks, in the ravines and in the places of the foliage not very exposed to light, they prefer plants that regularly receive fertilizers with high nitrogen content, in places with low humidity and poor ventilation. Even these bumps are often moved on the plants by the ants, which feed on honeydew, sometimes the presence of ants on our plants can be an alarm bell, which reveals the presence of parasites in areas not visible to us.
If the infestation is mild, it is possible to eradicate this parasite by removing it manually, taking care to disinfect the holes left by the insects with a cotton swab dipped in alcohol. If the infestation should be massive, it is good to intervene using white oil, perhaps activated with a pyrethroid or with malathion, for a more effective action. For an optimal result it is advisable to treat the plants with anticoccidics at the beginning of spring or in autumn-winter, in order to be able to destroy most of the eggs, avoiding to damage the useful insects, little present in these periods of the year.
Root mealybugs are usually eradicated by using contact insecticides, avoiding white oil, which could damage the roots themselves.
The biological fight against cochineal it is practiced using populations of Cryptolaemus montrouzieri, a ladybug that feeds on mealybugs; some small wasps pierce the badges to lay their eggs, the larvae will feed on the small mealybugs.
Massive mealybug infestations can produce abundant honeydew, which promotes the development of smoke.
These insects have had, and still have, a great commercial importance, since a food coloring, carmine red, is extracted from the female body; usually the "breeding" of cochineal develops on large opuntie.
White oil against mealybug
One of the most used remedies against coccycilia is white oil, an oily substance to be sprayed on plants that creates a patina on the leaves that suffocates and eliminates all mealybugs present on the plant. White oil is nothing more than a mineral oil that creates a patina on the leaves and therefore acts by suffocation on the pests but for this reason one must be very careful when using it. Particular attention must be paid to the plant as white oil is absolutely not a product to give when temperatures are high in summer.
The oil in fact creating a patina on the leaves decreases their leaf transpiration and consequently increases the possibility that the leaves "boil" or cook for the excessive heat which is not balanced by adequate leaf perspiration. White oil is a product to be given in the spring and autumn months even if nowadays there are also products suitable for the hottest months of the year in nurseries and garden centers which can therefore also be administered in summer.