white fly on plants

Aleyrodidae or white fly on plants

The white fly or Aleyrodidae is a parasite of plants of tropical origin, with a behavior very similar to that of the aphids, of which it is a relative. These flies in fact feed on the sap of the plants, with the production of honeydew and the consequent possibility of Sooty Mold.

Whiteflies, also called whiteflies, are not picky and can be found on many types of garden and orchard plants, such as tomatoes and chilies.

This is why they can become a big problem if they infest the garden, when an attack is identified it is good to intervene promptly, also because the whitefly is characterized by a very fast reproduction that facilitates its spread.

In reality, what is called whitefly or greenhouse fly is not a single species, there are different strains of fly that can infest horticultural plants in the same way.

Damage caused by whiteflies

Just like aphids, whiteflies also usually settle on the underside of the leaf, from here they damage the leaf and secrete the characteristic sugary honeydew, which then can lead to smokiness or cause virosis to plants. The damage to vegetables is therefore mainly in the transmission of diseases, therefore indirect. Insects are small and by sucking sap they hardly cause direct damage. When there are many, they can still weaken the plant to the point of causing the leaves to fall and death.

Which crops are affected

Aleirodis is a polyphagous insect, has no qualms about switching from one plant to another, and is much less selective than aphids. In addition to vegetables, it can infect many ornamental plants and does not disdain the young branches of the trees in the orchard. There is a variety known as citrus whitefly that mainly affects the citrus grove, as evident from the name.

This crop pest loves the closed and sheltered environment of the tunnel and for this reason, it often attacks greenhouse vegetables, not for nothing one of the names commonly attributed is “greenhouse fly”. In winter, the Aleyrodidae can settle down to overwinter among the internal leaves of the cabbages, which provide shelter until spring.

Recognize the presence of the insect

Whiteflies can be easily recognized: they are very small insects but still visible to the naked eye, generally whitish in color. Often they settle under the leaves, on the underside, for this reason, they remain hidden from a distracted glance, just like aphids. However, these are flying insects, unlike aphids when watering the plant whitefly individuals take flight and reveal themselves.

The whitefly fears the cold, which is why its incidence is lower in winter and generally in the north, while it proliferates in temperate areas, in greenhouses and citrus groves, in the north we find it, especially during spring and summer.

On large horticultural crops, especially those in greenhouses, it is worthwhile to place chronotropic traps for monitoring purposes. This allows the presence of the parasite to be identified in a timely manner and to intervene before it is able to proliferate excessively.

Defend the garden from the white fly

Against the whitefly you must not use pesticides: there are several natural defense methods that allow you to avoid the use of dangerous treatments. Let’s find out in detail which practices and which products we can use.

Manual removal

The whitefly is similar to aphids in behavior, but it is an insect with wings, this means that the technique of washing away the small parasites from the leaves or removing parts of the affected plant has limited effectiveness: if it allows eliminating eggs and larvae easily adult individuals move more easily from plant to plant. On a small scale, however, it is worthwhile to intervene manually to remove parasites when they are numerous.

Biological insecticides against whiteflies

This insect is quite resistant to insecticides and is also able to adapt over time to an active ingredient, so to make effective treatments it would be important to vary the product.

Furthermore, it is not easy to kill the whitefly with a natural product that acts by contact, as all organic pesticides do, because the small insects hide on the underside of the leaf and often escape treatment.

Among the products allowed in organic farming we can use to kill Aleyrodidae:

  • Sweet orange essential oil
  • Neem oil
  • Pyrethrum
  • Among the vegetable macerates that can be self-produced, the repellent effect of the garlic and hot pepper macerate is worth mentioning.

Chromotropic traps

Whiteflies can be captured with chronotropic traps, which are hung in the garden above the infested plants and have a similar operation to that of flypaper. For example, the insect trap for whiteflies and absolute suits is interesting.

This system is useful both for monitoring and for mass trapping but you have to be very careful because as it catches whiteflies it can reap innocent victims among useful insects. In particular, if there are flowering plants, avoid using sticky traps of this kind.

Natural antagonists

To fight the whitefly, it is also possible to field a biological fight by exploiting the shapely Encarsia, a small wasp that lays its eggs among those of the whitefly and is a natural antagonist. In addition to the wasp, entomopathogenic fungi can also be used: the Beauveria Bassiana and the verticillium can work. These remedies are feasible on a medium-large scale, it is not advisable to use them in a small garden. However, even in the family garden, you can aim to attract a very common whitefly predator: ladybugs.

Preventing whitefly attacks

In addition to the actual biological control, it is useful to try to prevent the presence of this parasite, especially in tunnel crops, which are particularly harassed by whiteflies. To prevent the advent of whiteflies inside greenhouses, it is good to ventilate frequently by letting in the cold that is unwelcome to the insect.

Another form of prevention is to attract ladybugs to your garden, as already explained they are natural predators of the fly.

Finally, if you notice plants that frequently host whiteflies, it is worth considering eliminating them, in particular the species that offer a winter shelter in which to overwinter.


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