How do you kill beetles

Causes devastating forest damage
Bark beetles - printer and engraver

Bark beetles occur worldwide and on all deciduous trees and conifers. Many species of bark beetles only attack one or a few host tree species, others have a very broad spectrum of tree species.

Most species colonize damaged or dead conifers or deciduous trees. But some are dangerous forest pests - they also attack healthy trees. Under favorable conditions, they multiply by leaps and bounds and can cause extensive forest stands to die.

Bark beetles burrow through the bark of their host tree species such as the spruce and create breeding channels for their offspring there. A distinction is made here between wood-brooding bark beetles, whose burrows penetrate into the wood, and bark-brooding bark beetles, which create their brooding paths under the bark.

Answers to frequently asked questions about bark beetles (FAQ)

Major pest book printer

In spruce forests, bark beetle damage repeatedly causes devastating damage. The main culprit is the book printer; Since the dry year 2003, the much smaller copper engraver has also contributed significantly to the death of large spruce stands. The printer is the most dangerous bark beetle and forest pest in the moderate latitudes. The starting point for mass increases are damaging events such as windthrow, snow breakage or drought.

Remedy only through "clean forest management"

  • The only effective countermeasures at present are the "clean economy" methods. It is important that infested trees are recognized as early as possible (from drill dust trickling out) and
  • trees infested by bark beetles are felled as quickly as possible (before the beetles fly out again and cause new infestations),
  • the wood is removed from the forest,
  • if there is a risk of copper engraving (a smaller bark beetle), summit material is also rendered harmless (chopping, burning).

Video tutorials on bark beetle search and control

Since personal advice to Bavarian forest owners is currently only possible to a limited extent as a result of the corona crisis, the forest administration has created two video clips on this pressing topic. The two films, each around three minutes long, explain clearly what is important when searching for and fighting bark beetles.

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Possible tax relief when using calamity
Regardless of the offers of the forest administration for forest-related advice and forest support, forest owners affected by the use of wood as a result of force majeure (calamity use) may receive tax relief. Forest owners can apply for a tax rate reduction for the use of calamities from the competent tax authorities in accordance with Section 34 b of the Income Tax Act. The Bavarian State Tax Office provides detailed information.

10-point package of measures to combat bark beetles

With the 10-point package of measures for bark beetle control, the Bavarian state government has adopted extensive aid measures to support forest owners and forestry associations. For the timely processing of beetle trees (trunk wood and crown material), funding of up to € 12 / fm trunk wood can usually be granted.


Funding for "insecticide-free bark beetle control" is € 5 / m3. This includes moving infected wood from the forest to previously agreed, forest protection-effective intermediate storage, debarking by hand, motor-manual or machine, as well as effective stripping with a chainsaw. The same applies to the insecticide-free, forest protection effective processing of residual forest wood not intended for marketing (especially crown and branch wood). These include chopping, mulching, burning or shredding with a chainsaw.


The subsidy rate for the use of special debarking harvester heads, so-called "debarking heads", is 4 € / fm.


The preparation of the insecticide-free bark beetle control is funded with 5 € / m3. This compensates for the additional costs that arise in advance and when processing the beetle wood. This only applies to amounts of wood that are then processed in an insecticide-free manner to protect the forest, i.e. exclusively in connection with the measures of debarking, moving and / or processing residual forest wood.


The existing funding opportunities for the creation of storage spaces are supplemented by the specialist advice center for transport and storage at the Bavarian State Institute for Forests and Forestry. She supports the forest associations in all matters relating to the transport and storage of logs on site.

Specialist advice center for wood storage


The forestry associations (FZus) receive extended funding for the implementation of information events on spruce bark beetle control and the organization of joint, insecticide-free control measures. In addition, the funding for simple forest management contracts was increased once again. For this purpose, the forest associations receive up to 75 euros per member.


Landwirtschaftliche Rentenbank Frankfurt offers forest owners affected by drought and severe weather events low-interest loans to finance forest management expenses. With the new "Forestry" promotional line, Rentenbank is supplementing the existing federal and state promotional offers and is particularly supporting efforts to make the forest more site-specific and more resilient. The promotional loans are aimed at forest owners, forestry associations and forest cooperatives as well as tenants of forest areas, regardless of the chosen legal form. For example, expenses for first afforestation, for climate and location-adapted forest conversion, for jointly used machines or wood storage facilities as well as for storage and reforestation in the event of extreme weather or other damage events are financed at particularly favorable conditions.

For more information, call the service number for credit inquiries: 069 / 2107-700 or visit


To ensure that the package of measures can be implemented quickly, the departments for food, agriculture and forestry received additional staffing and financial support as early as 2018. The budget for additional skilled workers was again significantly increased this year.


The comprehensive specialist information and tools in the Bavarian Forest Information System (BayWIS) are important aids for the district managers when fighting bark beetles. So z. For example, suitable dry storage areas outside of the forest are efficiently searched for or damaged areas documented and, if necessary, the processing monitored.


The State Institute for Forests and Forestry (LWF) oversees several monitoring systems for monitoring the various insects relevant to forest protection. It regularly provides up-to-date technical information on the need to control them and provides up-to-date information on the bark beetle situation at


Round tables and increased public relations work bring all stakeholders together and facilitate communication and cooperation between the self-help institutions and authorities. The ÄELF now also offer supraregional round tables.

Ultimately, the predicted increase in beetle masses can only be managed through close and efficient cooperation between the forest owners, forest administration, forestry associations, associations and also the timber buyers. The same applies to the reforestation of damaged areas with climate-tolerant mixed stands. The Free State provides considerable funds for this.

Biology of the bark beetle

Bark beetles are part of the natural endowment of our coniferous forests. The development of their populations depends on many natural factors. In particular from:

  • Favorable weather (temperature> 16.5 ° C)
  • Suitable breeding room offer

After major damaging events, e.g. B. Windthrow or snow break, a certain increase in the population can never be completely avoided. The bark beetle is part of the natural dynamics of the forest. Without adequate forest protection measures, however, mass reproductions can occur very quickly, with serious economic, cultural and ecological damage. In spruce forests there is a very high risk of developing a bark beetle calamity, especially of the printer, after storm or snow break damage.

Risk of mass reproduction with standing infestation

Depending on the current local beetle density and weather conditions (months from May to September), if the windthrowed wood and broken wood is neglected, insufficiently or incompletely processed, mass multiplication can already occur in the following year - but often only after 2 to 3 years. These lead to standing infestation and possibly extensive death of healthy trees.

In order to avoid this, it is absolutely necessary to take "forest protection" into account in all operational decisions. Failure to do so not only leads to further damage to existing buildings: They can burden the timber market for years and have serious consequences under public and private law. Inadequate forest protection measures lead to high economic losses.

Prevention and control

Check for standing infestation

After storm or snow break damage, there is always the risk that a bark beetle calamity will develop. Standing infestation controls are therefore absolutely necessary.

In 2003 the standing infestation was mostly triggered by the copperplate engraver. Typical infestation pattern: Well-developed brood patterns of the copper engraver are star-shaped. Due to the competition in breeding rooms with engravers, the printer's mother aisles are often very short.

Debris search

The drill dust search is the only way to identify infested trees at an early stage, i.e. before the adult beetles return, but in any case before the young beetles leave.
In spring, a few days after the onset of the first swarming flight, then every 2 weeks (in the calamity phase: 1 week rhythm). Drill dust is only thrown out as long as the ramming chamber and the mother passages are created.
Do not search for drilling dust shortly after rain or strong wind, as drilling dust will be washed off or blown away. Take into account the swarming phases of the book printer when scheduling the search for drilling dust: Do not search immediately after the swarming flight begins, but only after a few days.
Approach the trees to be checked individually! Look for traces of drill dust behind bark scales, at the base of the trunk, on cobwebs. Green needles that have fallen down are also a sign of a standing infestation in summer (but then some of the beetles have already flown out again). Mark infested trees and enter them on a special infestation map. This so-called infestation map and ongoing documentation are important tools during the entire calamity. This is the only way to understand where there was standing infestation in the past year. Old foci of infestation are often the starting point for new standing infestations.
Previous year infestation species; known infestation species from earlier years; south-exposed and other heat-favored locations; torn, sunken forest edges; Surroundings of windthrow nests. Concentrate the standing infestation control on spruce stands suitable for book printing (from age 30).

Mapping of the standing infestation from the air

In inaccessible terrain and in order to get an overview of the entire infested area in a short time, mapping from the air is very suitable. Infested trees can be recognized by the discoloration of the crown. From around mid-July, in addition to the previous year's infestation, there was also a spring infestation of the same year. However, by this time the young beetles have already flown out. Recognized nests must be recorded on a map.

This map (scale 1: 10,000) supplements the infestation map (see above) or forms its basis. Mapping from the air does not in any way replace the drilling dust control, since with this method only trees can be recognized after the beetles have escaped! In late summer (September) in calamity areas, it can be useful to perform another inspection flight in connection with the last search for drilling dust.

In the mountains, the so-called "counter-slope control" is a further, well-suited aid to identify standing islands (after the young beetles have gone out!).

Processing of beetle wood

Any beetle trees discovered that the beetles have not yet flown from must be felled immediately. The same applies to preventive waste wood processing. The wood must then be stripped immediately or removed from the forest. Treatment of individual strains with insecticides is ruled out.
After the last swarming flight in late summer (from around early to mid-September), the work capacity should be concentrated on finding the beetle trees. Now only mark infected trees and process them in the course of autumn and winter.

Burning of branches, tops or bark

The legal basis is the "Ordinance on the Disposal of Plant Waste Outside Authorized Disposal Facilities" (PflAbfV). Vegetable waste from the forest operation may be incinerated where it has accrued, provided this is necessary for forestry reasons. The wording "where they occurred" can also mean at the edge of the forest or immediately next to the affected forest area.

Information about the regulations and precautionary measures can be obtained from the district offices and independent cities. These can also allow exceptions in individual cases, provided that this does not impair the public interest (e.g. safety aspects).

For guidance, a leaflet from the State Institute for Forests and Forestry (LWF):

Use of pheromone traps

As a rule, pheromone traps are not suitable for noticeably reducing the population of book printers through mass trapping. The skimming rate is minimal. The setting up and continuous control of numerous pheromone traps is costly and time-consuming and ties up work capacity that should better be invested in intensive standing infestation control.

However, individual traps set up in south-facing locations can be helpful to monitor the current swarm activity and to carry out the drill dust controls accordingly. These "wise traps" have to be checked 2 to 3 times a week!

Forest protection strategy

The most important goal is to avoid a nationwide calamity. To do this:

  • as high as possible of the bark beetle population and
  • the breeding space potential of the bark beetles should be reduced as much as possible.

This is the only way to achieve an initial situation that is as favorable as possible for the forest for the next "beetle year".

That means:

  • The forests must continue to be checked intensively (preferably weekly) for infestation.
  • Detected nests of infestation must be cleared out immediately and carefully.
  • Infested wood is to be removed from the forest as soon as possible or as soon as possible after felling (at least 500 m as the crow flies). Alternatively, infected logs can be debarked and the bark either burned or thrown in large piles. The heat generated in the pile (up to 65 ° C) kills any beetles that might be ready to fly.
  • In the event of a windthrow or snow break during late autumn and winter, all damaged wood must be removed from the stands by the end of March. In the spring this would serve the printer and the engraver as breeding material and thus as a "start-up aid" for further multiplication.
  • Because of the risk of copper engraving, branches and peaks must also be reliably chopped, transported or burned.

The burning of branches, peaks or bark is only possible when there is a low risk of forest fire.

Unless everything is infected orMaterial suitable for breeding can be removed from the forests in a timely manner, insecticides approved for bark beetle control can also be used (pile spraying). The treatment should be carried out in compliance with the water and nature conservation requirements so that the active ingredients are not already broken down by the time the bark beetles go out (observe the instructions for use).

Tips for private forest owners

Legal consequences of neglected forest protection measures

Monitoring and controlling bark beetles are legal obligations of the forest owner. Failures not only lead to tangible damage in your own forest or in the forest of your neighbors. You can also trigger sovereign coercive measures (up to substitute performance) and fines. In addition, there may be civil law claims for damages from injured neighbors.

The state offices for food, agriculture and forestry are involved in control and monitoring within the framework of their capacities. They also inform private forest owners about observed infestations and the necessary measures.

Tips for urban forest owners

Forest owners who no longer have forest know-how and / or equipment are just like all other forest owners responsible for protecting their forests and fulfilling their legal obligations. This also applies to the "urban forest owners" who z. B. live in the city and have a piece of forest far away in the country. In such cases, we urgently recommend that you ensure bark beetle control and control through contracts with suitable service providers (e.g. forest maintenance contracts). The local departments for food, agriculture and forestry are available for information and advice, but cannot take on such operational tasks themselves.

Forest service providers

The forestry associations, forest owners' associations and forest entrepreneurs support you in organizing the processing and marketing of damaged wood.

What's next after the bark beetle?

  • Bark beetle areas must also be checked regularly in the following years, as experience has shown that there is an increased risk of new infestation at the edges. The cause is often the hesitant processing of infected spruces that still have a green crown.
  • Cleared areas must be put back into forestry within three years. Small areas, the size of which corresponds to natural forest pelts, are not included. If necessary, existing natural regeneration is to be supplemented by planting suitable tree species.
  • Bark beetles are part of the natural endowment of spruce forests. The risk of mass reproduction can never be completely avoided in forests rich in spruce. We therefore recommend the gradual conversion of coniferous forests into mixed forests. Mixed forests are more stable against storms, drought or insects and are therefore better equipped for the consequences of climate change. The offices for food, agriculture and forestry offer free advice on this.