Insecta, Coleoptera, Scolytidae .
Description, Biology, Life Cycle, Damage, Common Names, Images
- Host plants: olive, Fraxinus spp., privet (Ligustrum sp.), lilac (Syringa), Phyllirea sp.
- Adults: they spend the winter in small holes excavated in the wood or in the axils of the vegetative buds (*) . The holes on the stem are covered with debris and faeces resulting from their normal feedingactivity and visible from outside of the plant.
In the spring they leave the shelter and infest new hosts, perforating the bark and excavating a place for mating (*) . Subcortical galleries are excavated by females where they deposit the eggs, singly, but in total over ten.
- Eggs: incubation period from 8 to 13 days.
- Larvae: during their development larvae excavate new galleries in the stem perpendicular to the maternal gallery (*) .
- Pupae: The larvae pupate in small excavated galleries in the stem formed during feeding and after, 13 to 18 days, adults will be produced; they emerge from the host 3 to 5 days later.
- This pest is xylophagous both in the larval and adult stages, and has 1 to 3 generations per year according to the availabiblity of weakened trees or other vegetative material.
Adults of the lst generation excavate an exit hole to the exterior. At first, the adults attack the base of small branches or inflorescences, which the become dessicated. The second generation adultes occur from September onwards. they have similar habits to those of the former generation. New adults of a partiel third generation may aoccur in November. After this timre it is possible to find in hibernation surviviving second-generation adults and third-generation larvae.
There are two different kinds of damage, the first affecting debilitated or weakened olive trees and the second well-developped, vigourous trees.
- In the first instance, damage is caused by larval feeding and by adults which attack the already weakened stems and branches of debilitated olive trees, increasing damage and causing further decline and sometimes death of trees.
- In the second, losses are due to adults producing incisions on small, healthy branches when feeding, causing the tips to dessicate, or to adults damaging axillary buds when trying to initiate small galleries or holes in which to hibernate.
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