What is "psylla pyri"

Flea-louse \Flea"-louse`\, n. (Zo["o]l.) A jumping plant louse of the family Psyllid[ae], of many species. That of the pear tree is Psylla pyri.

Psylla pyri is one of the most important pear phytophagics; because of the numerous chemical interventions, its dangerousness is increased, reducing the phytopathogenics's populations of this bug. It is not, however, considered a harmful bug since it is easily censurable with simple interventions, which have favored a resumption of the Psylla's natural enemies.

Psylla's adults are long, around 2.5-3 mm, and of ochre or brownish color; the wings are transparent and positioned to sloping roof on the body.

The larvae are flattened and of yellowish-orange color, that darken with time to a brown-blackish color.

In the juvenile stadiums they will cover of honeydew, to protective purpose; the eggs will cover too of honeydew and are of yellow-orange color, besides, are of pointed form to an extremity, while in the other there is a tail.

Psylla colonizes the buds, the young leaves, the young branches and, sometimes, the fruits too.

The damages can be direct and indirect: the first ones concern the vegetative arrests and deformations, with small necroses on the buds and on the leaves, following the punctures; the seconds provoke abundant production of honeyedew that provokes asphyxias on the green organs and scorching on the tissues. Besides the honeydew depreciates the fruits and it makes useless the treatments; the honeydew, finally, facilitate the establishment of the mushrooms, that decrease the photosynthetic output, altering the metabolism of the plant.

Psylla is a vector of illnesses too, like the Pear's Blackberry. This bug winters as adult and it completes 5 generations a year; activity is taken back in March, with superior temperatures to 10 °C.