Aphids, also known as plant lice, are parasites very harmful to the plant world.
They are very small insects, which usually do not exceed 4 millimeters in length, oval in shape and of various colors; they spread very easily in areas where the climate is hot and humid.
Aphids are extremely widespread and cause aesthetic and economic damage to crops. Among the ornamental plants, the rose is one of the most exposed to this risk, but they often infest also vegetable and fruit plants, causing very serious problems in the agricultural sector. It is possible to combat them, but timeliness is essential.
Their reproductive cycle is extremely short. Usually the winter reproduction gives origin to a female brood without wings, the spring and summer one, on the contrary, which happens asexually (by parthenogenesis), produces eggs from which specimens of both sexes will be born.
The aphids may or may not be equipped with wings, the first ones can easily move from an infected plant to a healthy one, propagating the epidemic which, in fact, often spreads also to the surrounding ones. The presence of many specimens on the same plant can lead to a lack of space: this triggers the birth of a generation of winged aphids able to migrate to other host plants.
The aphids tend to colonize the apexes of the plant and the lower part of the leaves; it is possible to notice their presence thanks to the colour which generally contrasts sharply with the green of the plant, even if some families of aphids, instead, tend to camouflage themselves with the leaves, making it more difficult to identify them.
The aphids feed on the sap of the plants by sucking it through the rostrum from the shoots and leaves, for this reason they prefer the soft leaves. The absorption of the sap leads to the weakening of the plant which, if left untreated, suffers and suffers obvious aesthetic damage. Aphids absorb lymph proteins and process their sugars, producing a substance called honeydew, a compound that attracts other insects including ants and wasps.
The honeydew is also an ideal soil for soot, a fungus that creates a black patina on the surface of the leaf and blocks the light, compromising the photosynthesis chlorophyll. This makes the weakening of the plant even faster.
In the case of aphids, disinfestation takes place through specific synthetic or biological phytosanitary treatments that are sprayed on the infested area.