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Classification and host plants
Species: C. norvegicus - C. fulvumaculatus
“Phytopathology, agricultural entomology and applied biology” – M.Ferrari, E.Marcon, A.Menta; School edagricole - RCS Libri spa
Host plants: Pear, Apple tree, Stone fruit, Citrus and others.
Identification and damage
The Miridi are small-sized insects (6-8 mm in length), brownish-blackish (C. fulvumaculatus) or greenish-yellow (C. norvegicus) depending on the species; the body has a characteristic oval shape with long legs and very pronounced threadlike antennae. The damage is evident on the fruits and on the shoots; it is determined by the trophic stings, especially of the nymphs.
The fruits, especially if hit at an early phenological stage, are deformed stopping their development in the points corresponding to the stings; in the pulp there are characteristic groups of dead cells, of stony consistency (especially in pears), which give rise to a symptomatology called lithiasis. This symptomatology should not be confused with the infectious one of viral origin or with the borocarence one.
On stone fruit, the bites of myridae always cause deformation of the fruit accompanied by gum emissions and splitting of the fruit, especially if the attack occurs in the early stages of development of the fruit itself.
The Mirids can also attack young shoots directly; in this case, the stings cause a stop of the development or a deformation which, especially in the young plants in breeding, can cause the loss of part of the cimal, with serious damage to the form of breeding.
Fruit myrtle Calocoris norvegicus Gmel. (photo http://gwydir.demon.co.uk)
The Miridi winter in the egg stage, in the ravines of the host plants, in the wood shelters of the support poles or on herbaceous or shrub plants on the edge of the cultivated fields.
The nymphs appear in late winter-early spring, depending on the environment, and begin their activity. Adults appear in June; these may possibly originate a 2nd generation between July and August. The Miridi therefore make one or two generations a year.
The fight against the Mirids is chemical and follows the criteria of the guided fight. The fight takes place against the first generation nymphs.
The technique involves sampling, to determine the presence of the nymphs or to establish the beginning of their activity, by identifying the damage.