Olive mite

The olive mite (lat. Aculus olearius) belongs to the family of four-legged or gall mites (Eriophyidae), part of the order Acariformes.

This microscopic pest is nearly invisible to the naked eye, as the size of an adult rarely exceeds 0.15–0.2 mm.

The mite's body has a worm-like, elongated shape and is pale yellow or pinkish, which allows it to blend in with leaf surfaces.

Its life cycle consists of two main stages: eggs and active mobile individuals that move using two pairs of front legs.

Fertilized females overwinter by hiding in bark crevices, bud axils, or under the scales of young olive tree shoots.

The primary host is the common olive tree (Olea europaea), although the mite can also be found on wild olive species.

The pest prefers to feed on tender young tissues, concentrating on the underside of leaves, as well as on flower buds and ovaries.

While feeding, mites inject saliva containing enzymes into the plant tissue, causing physiological disturbances in the epidermal cells.

The greatest economic impact occurs in nurseries and young orchards, where infestations can lead to stunted growth and seedling deformation.

Massive infestations reduce the overall vitality of the tree, making it more susceptible to secondary fungal infections.

Mite activity begins in early spring as soon as average daily air temperatures exceed the threshold of +10 to +12 degrees Celsius.

Periods of dry and moderately warm weather provide the most favorable conditions for rapid population growth.

Within a single growing season, the pest can produce 6–8 generations, which explains how quickly new shoots become infested.

Population peaks usually occur in late spring and early summer when new leaves emerge and inflorescences are forming.

By autumn, as temperatures drop and daylight decreases, female fertility declines and they migrate to their wintering sites.

In the early stages of infestation, characteristic discolored spots appear on the leaves, which gradually turn brown or rust-colored.

In cases of severe infestation, leaf curling, deformation, and premature leaf drop are observed, particularly in the lower part of the canopy.

Disruption of flower development leads to bud drop or the formation of poor-quality fruit, significantly reducing the market value of the harvest.

In areas where the pest congregates, the tissue becomes coarse, loses its glossy sheen, and appears dusty.

• Yellowing and spotting of young leaves.
• Curling of leaf margins.
• Dropping of ovaries and flower buds.
• Reduction in overall shoot growth.

The most important control step is agrotechnical management, including regular sanitary pruning to improve canopy aeration.

The use of balanced fertilizers helps increase the tree's resistance to damage, while avoiding excessive nitrogen applications.

When pest numbers are high, specialized acaricides registered for use on fruit crops should be applied.

Chemical treatments are most effective at the beginning of the growing season before the mites hide in bud axils or curled leaves.

Biological control methods include maintaining populations of predatory phytoseiid mites, which are natural enemies of Aculus olearius.