Unexpected attack of new generation fir bark
The Swedish Forest Agency is alerting a new generation of spruce bark drills that are currently affecting the country's spruce forests - where the damage in some parts is even expected to be greater than last year.
- Some of the spruce bark drills have been wintering, but some are attacking new trees right now. We had not expected anyone to attack new trees now that the new generation was ready so late in the season. This is something new, says Gunnar Isacsson, ecologist and insect expert at the Swedish Forest Agency, to TT.
An approximately four millimeter long beetle may not seem so dangerous. But in large quantities it can take cabbage on even large and healthy spruces. Last year, the weather was pure dream for the spruce bark drill, and 3 to 4 million cubic meters of forest worth billions were destroyed, which was more than the major forest fires last year. But the alarm has come that the damage can still be much greater this year.
This year's main swarm of spruce bark had its culmination in June. But now the Swedish Forest Agency's surveillance shows that a new generation of insects have started attacking trees instead of going down into the ground as expected to winter. In the authorities district of Blekinge, Kalmar and Sörmland, the damage is estimated to be worse than last year.Should be felled
But new attacks are also found in the districts of Jönköping, Kronoberg, Skåne, Värmland, Örebro and Östergötland - as in parts of Halland, Västmanland and Uppland.
Therefore, Gunnar Isacsson has a straightforward advice to the forest owners:
- Then you have one more generation of baggies that will be finished sometime in September - October and that go into wintering then. And then comes next year's attack as a letter on the post, Isacsson replies.
The dry and warm weather last year multiplied the amount of spruce bark drills.Popular nursery
The trees defend themselves by trying to drown the insects with resin, but if the gnawing lugs are sufficient enough the tree will eventually be unable to withstand and the firs affected by drought are extra vulnerable.
A very popular nursery for the spruce bark drill is storm felled forest. But the clearing after the Alfrida storm in January in Stockholm County has been very slow.
- It's very serious. Since we had the hot summer last year, there was a very large increase in spruce bark drill then and they have been able to reproduce very well this year too, responds Glöd.