The damage of olive leaf moth is due to the fact that it feeds during its larval state from the tender shoots of the olive.
Characteristics of the different states of the Palpita unionalis
Egg: they are deposited by adults in the underside of the leaves of the olive shoots. Usually the eggs are isolated and dispersed in different shoots. The size of the egg is 0.6x1mm. Its color is whitish-yellowish and has shape is oval, flattened and with a reticulated surface.
Larva: at birth they are color yellowish, which changes to bright green during their growth phase. As a protection, they weave a fine silk cocoon that joins the leaves of the buds, feeding inside. The larvae of Palpita unionalis manage to reach 2 cm in length when their development ends. Their uniform color and translucent hue allow them to be easily distinguished from other larvae.
Cocoon: For your metamorphosis, the glyph larvae crisp together by weaving a fine silk cocoon. This cocoon can be located between the leaves of an outbreak, in some crack present in the trunk of the olive tree or more frequent among the leaf litter of the soil.
Adult: it is a pearly white butterfly and about 3 cm in size.
Biological cycle and generations of Palpita unionalis
In Andalusia, the different states of the Palpita unionalis can be found practically throughout the year. That is why the generations overlap each other and are not as periodic as those of other species, for example, the Prays. Even so, the olive leaf moth also has periods of maximum activity, which obviously coincide with those of greater presence of food (growing times of the olive tree).
During the months of spring-summer there is the population peak of the Palpita unionalis. During the fall there is also an increase in activity, although of lower incidence. With the low winter temperatures the activity of this butterfly practically paralyzes.
Damage caused by the olive leaf moth
The nurseries and the new plantations are the ones that suffer major damage. Small olive trees can see their formation damaged due to the destruction of shoots carried out by the larvae.
When the populations are very large, the larvae also feed on the pulp. This can cause damage of some impact on crops intended for greening.
In the traditional olive grove and consolidated plantations, the damages produced by the olive leaf moth usually go unnoticed.
Olive leaf moth treatments and control
The biological control carried out by other insects, the cultural measures and as a last resort the phytosanitary treatments allow to deal with this pest of the olive tree.
Among the different existing parasitic hymenoptera, Apamarales hemara and Oomyzus sp are the ones that control this pest present in the olive grove.
Promoting the presence of young shoots increases the availability of food and induces a population increase of the Palpita unionalis.
Some risk factors are:
1.- Olive tree fertilizer with excessive nitrogen.
2.- Olive grove in irrigation: it favors the growth and the presence of tender shoots in the olive trees.
3.- Application of pyrethrins: this type of insecticide damages the populations of the auxiliary fauna parasitic insects that are in charge of carrying out the biological control.
The application of chemical products should be done only when the populations of Palpita unionalis damage some consideration. The treatment period ranges from mid-May to the end of November.
The phytosanitary treatments used must be carried out with products authorized by the ministry. In addition, the indications made by the manufacturer must be followed strictly.
We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.