what to buy for aphids and whiteflies
aphids and white flies are two quite different insects, both in their biological cycle and in terms of the environmental conditions that favor their development. Typically the most prolific season for aphids is spring, as these insects love the younger and tender parts of plants, such as floral buds and buds; in addition to this, the high environmental humidity and a warm but not torrid climate are ideal for their development. Most of the insecticidal products found in the nursery (but also in the supermarket) are formulated to kill aphids, because they are among the most common and widespread insects on ornamental plants and in the garden. One of the most deadly products on aphids is Imidaclopryd, a nicotine-derived toxin; its use must be carried out with caution, because it is a broad-spectrum active ingredient, and therefore besides aphids (and also white flies) it will kill all the insects it will come in contact with, including useful ones, such as bees , and also included aquatic organisms that may come into contact with the product once it is washed away from the plants and finished in the aquifer. For this reason, products based on imidaclopryd should be used very carefully, using only the strictly necessary quantities, and avoiding periods in which there are flowering plants in the garden that attract bees. Pyrethrum-based products also work against aphids, and there are also products suitable for organic farming, such as bitter quassia extract or neem extract; used in organic farming, however, it does not mean completely harmless to useful insects, therefore, even if you choose an organic product, avoid spreading it on flowering plants, avoiding windy days that would cause a migration of the product on plants not affected by insects, avoid spread insecticide everywhere as a preventive method. The value of organic products is due to their lower toxicity for humans, beneficial insects and aquatic fauna, as well as their minor residual action: today they spray the product on the plant, which will be protected against aphids for only a few days ; the quassi has the advantage of remaining on the foliage for a while, making it unattractive for sucking insects. However, expect at least a couple of treatments, because some insecticides work only on adults, and therefore the eggs remain and you will end up with other aphids to kill. Aphids often accompany ants or better, vice versa), so check also ninth true ants' nests in the garden, and in case use special powder insecticides to remove them. White flies are insects that are very different from aphids, they love a more dry climate, and above all their infestation is often present on plants left in greenhouses or in poor ventilation conditions; often the plants of the greenhouse moved outdoors in spring after a few days are free from these small insects. Also in this case neem extract and products based on pyrethroids work very well, if it were not that they act only on adults, and not on the intermediate stages of development. A new active ingredient, called Flonicamid, works on all stages of development, promising a much faster action to eradicate these insects; I've never tried it, so I don't know if the promises are sincere. IF you want more natural methods, you can use antagonist insects, even if in Italy it is not so easy to find them, it is a tiny wasp for white flies, and ladybirds for aphids and other insects.