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Pine Tree Plague
Thursday, 25 March 2010

The “Barrenillo” (Tomicus Destruens)

You may have noticed a sudden weakening in the appearance of the crown on your pine trees within your property; showing less young growth and the colour of the foliage has changed to a much lighter shade.

It is possible that you will find bits of yellow resin on the trunk, near to small holes. You will also have noticed that in the summer the tips of the needles were dry and fell off on windy days. All these signs indicate that your pine is infested with an insect locally known as "Barrenillo".

What to do if you have detected “Barenillo” in your pine trees

If the damage is observed in the twigs, try and locate the source of the plague and if you find it ask the owner to proceed with its elimination.

Please contact the "Delegación municipal de Medio Ambiente", if you have noticed large quantities of resin on the trunk.  They will inspect the tree and determine how to proceed with the extermination and in which season to deal with it.

Remember trees are fundamental to the environment. If you have to fell a pine tree because of a plague, please replace it with another of the same species. That way you will be helping to maintain and renew the forestation mass within Chiclana de la Frontera.

Fig. 1 Chart showing the life cycle of “Tomicus Destruens”


J       F       M       A         M         J         J       A       S       O         N         D


                               ---Emergence of adults--


Eggs-------------------                                                             Eggs-----------


-Larvae in

galleries------                                                                      -Larvae in galleries-




                                 -Damage to the Crown----------


                                                                                          -Damage to the bark-


Ayuntamiento De Chiclana De La Frontera. Delegacion Municipal De Medio Ambiente. (Municipal environmental delegation)


It is a small brown beetle, measuring 3.5 to 5mm in length. In its biological cycle it passes through the stages of egg, larvae, pupae, and adult. The first three stages occur beneath the bark of pine trees and the adults spend part of their life in the branches and crown of the tree.

The adult female penetrates a hole in the bark and builds a sub-bark chamber where mating will take place. She will place between 25 to 45 eggs along the length of the chamber, from which the larvae will hatch in 2 or 3 weeks. They emerge and start to digest the living tissue of the tree, at the same time as excavating galleries perpendicular to those of the mother.  

At the end of their evolution they create a pupation chamber from where they will emerge as adults.

Once the adults are on the exterior they move up to the crown, invading the end twigs and feeding on the core, to gain strength and mature sexually. The adult may colonise up to 3 or 4 fronds until they lay new nests within the trunk.                          


Their presence is detected, on occasions by droplets of resin on the trunk, the resin being the result of the tree trying to repel the invasion. The exit holes of the adults are more difficult to detect as they are not accompanied by secretions of resin.

When lifting the bark from a pine that has been affected by "Tomicus" you will observe the galleries of the mothers following straight lines in the same direction as the grain of the trunk. The galleries of the larvae are transversal to those of the mother.

The most characteristic symptom is produced in the fronds at the crown, towards the end of spring and the start of summer. In the base of the stem entrance holes made by the adults can be observed along with resin secretions. Also sometimes exit holes can be seen when the adult abandons the frond to colonise another. From a distance fronds and needle heads can be seen as discoloured and drooping.

In summary we can say that there are two external diagnostic elements: The appearance of resin specks on the trunk between autumn and spring, and the yellowing with posterior loss of needles between the end of spring and the start of summer.

Regarding damages we can distinguish between damage caused to the trunk or to the branches. On the branches the damage is limited only to the growth of the tree, which normally recovers fairly well after the attack. To the contrary the when "Tomicus" attacks the trunk, sooner or later the tree will die. It will suddenly dry out, (generally at the end of the summer) normally without any hope of saving it.         


It is important to point out that the "Barrenillo" can be considered a "parasite of the weak", because for it to penetrate and proliferate it needs to find trees with a low vitality.

There are no effective chemical treatments for this plague. Therefore the only advisable methods that are recommended are preventative and consist in:

•-    Location of concentrations and affected trunks, and their cutting and elimination, after the necessary permits have been granted. The elimination of the woody remains must be achieved by burning on spot, or at the city dump, or by shredder and chemical treatment with a product that contains "Fenitrotion", "Alfacipermetrin" or "Deltametrin" as its active ingredient. NEVER leave remains without eliminating or treatment in pine wood zones, as it would only be helping to further propagate the plague.

•-    Never leave remains of a size superior to 5cm in diameter on the ground after cutting.

•-    Keep your trees in a vigorous and healthy condition, watering them and fertilising them in the correct amounts (not too much, not too little).

•-    Maintain small woodlands within ideal densities. Excessive densities can create competition for light and water. Consequently reducing their vitality and making them susceptible to "Barrenillo", other plagues and illnesses.

•-     Do not damage the trees unnecessarily, fundamentally the roots, trunk and branches. The majority of dead pines caused by "Barrenillo" had previously been damaged by man or machine. In the case of accidental damage to a tree, clean the affected area and treat with a cauterising disinfectant product.

•-    Only prune the pine in the authorised season, without removing more than a third of the branches, making clean cuts close to the trunk (without damaging it).


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