ALB

Fig. 1 – Most Asian longhorned beetles found in Europe have white markings, as depicted here. Photo: Doris Hölling (WSL)

Displacement routes

outdoor ALB infestations in Europe

Fig. 2 - The map shows the known instances of outdoor ALB infestations in Europe to date. Map by Doris Hölling (WSL)

In 2001, this quarantine pest, which is classified as particularly dangerous, was detected for the first time in Europe in the field. Since then, new infestations have been discovered again and again.

This invasive species of beetle enters Europe within wooden packaging, primarily wooden pallets and crates used as packaging for granite from China. Although the beetles can only lay their eggs in living wood, their larvae can develop within wooden slats.

Correct heat treatment of wooden packaging would prevent beetles from developing during shipping or when in the destination country. Unfortunately, the corresponding markings are often just stamped on imported goods, with the packaging having undergone inadequate heat treatment, if any.

The non-native Asian longhorned beetle (ALB) infests different types of native hardwood trees (even healthy ones) and can cause dieback within just a few years.

Consistent control is needed

wooden packaging

Fig. 3 - Crates loaded with granite blocks. Photo: Doris Hölling (WSL)

Sightings of the Asian longhorned beetle must be reported and consistently controlled. All instances in Europe are reported to the European and Mediterranean Plant Protection Organization (EPPO), which has served as the central hub for European cooperation (among 50 countries) on European and Mediterranean plant protection since 1951.

All information in this article regarding outdoor infestations is based on EPPO reports.

Maple

Fig. 4 - Maple (depicted), willow, birch and horse chestnut trees are the most common host trees. Photo: Doris Hölling (WSL)

30 outdoor infestation sites in Europe have been eradicated to date, one is unclear. All others are still being monitored.

An infestation is only considered to have been eradicated once at least two successive generations have passed at a given site without any additional reported sightings of the pest or symptoms of its infestation. This period may be extended to three infestation-free generations in areas where development cycles are prolonged owing to the short vegetation period or where development time is variable.

Visual monitoring is carried out by specially trained tree climbers who are supported by specialist sniffer-dog teams , as in Switzerland the "Verband Spürhunde Schadorganismen Schweiz" www.vss-schweiz.ch, at some infestation sites. Scientists identify the beetles, larvae, pupae or eggs, as well as the noted symptoms and the age of the infestation. In addition, a DNA analysis is sometimes conducted to unequivocally confirm the identity of the pest.

Infestation sites in Europe

Austria - eradicated

All Austrian infestation sites are from Upper Austria

The Asian longhorned beetle was sighted for the first time in Europe at Braunau am Inn (close to the German border) in July 2001. It took 12 years to eradicate this infestation (completed in 2013).

However, another outbreak was reported 2013 in Gallspach, which is also located in Upper Austria. Since the beginning of 2021, this infestation is considered eradicated.

In 2012, a new record came from St. Georgen/Geinberg (located along the Inn river), where an exit hole and three trees infested with living larvae were found. The infestation has been considered to be eradicated since late 2016.

France

In France, this invasive beetle species first appeared in 2003. It is now known to occur in five regions. 

Centre-Val de Loire region
A relatively old infestation comprising many beetles, pupae and larvae was discovered in Gien industrial park. Beetles and infested trees were also reported in this area between 2004 and 2008, and symptoms of infestation were spotted again in 2016. Between November 2016 and October 2018 102 infected trees were found.

Pays de la Loire region
Beetles were discovered in Saint-Anne-sur-Brivet in 2004, where numerous larvae, beetles and eggs as well as over 77 infested trees continued to be found until 2005. Only one beetle was found in 2006. This infestation is considered eradicated since 2013.

Alsace-Champagne-Ardenne-Lorraine region
A beetle and two infested poplars were discovered at the port of Strasbourg in 2008. A survey unearthed several hundred larvae and eggs as well as dead beetles and pupae. Exit holes were spotted on three maple trees in 2010. In addition, larvae of varying ages and mature pupae were found inside the trunk. It is assumed that this infestation began in 2003 and remained undetected for two generations. The pests are believed to have come here in the packaging of granite from China. Since April 2019, this infestation has been deemed to have been eradicated.

Corsica region
In July 2013, two homeowners in Furiani reported numerous beetles and symptoms of an ALB infestation. Phytosanitary inspectors found additional infested trees with egg-laying sites and 60 beetles on the same day. Numerous companies that use wooden packaging are located in the vicinity of the infestation site.No symptoms were detected in 2018 and 2019. This infestation has been considered eradicated since October 2022.

Auvergne-Rhône-Alpes region
In late summer 2016, a Divonne-Les-Bains resident reported another ALB infestation. Many maples were infested. Living beetles and numerous larvae, as well as egg-laying sites and different old exit holes were also found in the town. In 2017 an infested maple was discovered, in 2018 4 infested maples and in 2019 8 infested trees (4 maples, 2 willows, 2 horse chestnuts). No symptoms were detected in 2020. Pheromone traps were also used in 2021. However, no new symptoms or beetles were detected this year either. In addition, intensive public relations work was carried out.

Germany

ALB

Fig. 5 - An ALB with slightly unusal markings was found in Bavaria. Unlike the individual markings found on the other beetles, the borders  between markings were not indistinguishable. Photo: Doris Hölling (WSL)

Asian longhorned beetles were first sighted outdoors in Germany in 2004. Sightings of the quarantine pest have now been reported in four federal states. One infestation site has been eradicated to date.

  • Bavaria

In 2004, all development stages and symptoms were spotted in Neukirchen am Inn. The intensive monitoring led to the fact that the infestation has been deemed to have been eradicated since the end of 2015.
Since then, this species of beetle has also been seen outdoors in the greater Munich area: in Feldkirchen in 2012 and in Neubiberg in 2014/2015. These two infestations have been considered eradicated since 2021.

In 2014, the invasive beetle species was additionally sighted close to Augsburg in the Schönebach area of Ziemetshausen. Some trees were heavily infested. In 2018, one beetle was cought in a pheromone trap. However, no infested trees were found until the end of 2020. This infestation has been considered eradicated since November 2022. This infestation has been considered eradicated since November 2022.

In April 2016 a plant inspector reported an ALB infestation in the Kelheim port area. This is a major outdoor infestation affecting 18 maple trees; some of their branches were already dead when the infestation was reported. It is assumed that the beetles came to the area in wooden packaging. Pheromone traps are used there, among other things. Since the beginning of 2021, this infestation has considered eradicated.

A new outdoor infestation was sighted in October 2016 in Murnau. Plant inspectors reported symptoms on 19 trees (maples and chestnut trees) in public and private green spaces and along a railroad track. This involved recent and old exit holes, eggs, and brittle branches and crowns. The 2017 monitoring included visual control as well as pheromone traps, trap trees and sniffer dogs. During monitoring from 2017 onwards, pheromon traps , trapping trees and sniffer dogs were used in addition to visual inspection. Since the beginning of 2021, this infection has also been considered eradicated.

At the beginning of August 2019 an infestation with ALB was detected in Miesbach. More than 30 beetles were caught. The infested trees included: maple, birch and horse chestnut.

  • North Rhine-Westphalia

In Mönchengladbach, a beetle on a maple tree from a private garden was reported in 2004. Apparently no population could establish itself.

Another outdoor infestation was spotted in 2005 in Bornheim in the immediate vicinity of a granite importer, 2007 one in Bornheim-Hersel (all maples), an additional infestation involving three heavily infested maples was discovered in Alfter in August 2009, in Bornheim-Roisdorf in May 2010an in Bonn-Tannenbusch in 2012. Between 2005 and 2012, 40 infested trees were discovered. Since 2012, only two infested trees have beeb dicovered - one in 2015 and one in 2017. Since 2021, this infestation has considered eradicated.

  • Baden-Württemberg

Reports of the quarantine pest have also come from the port area of Weil am Rhein since 2012.
In early summer 2015, sniffer dogs in Grenzach-Wyhlen found two empty egg shells, as well as a larva in its early stages of development, during routine checks of the district administration office. As the monitored areas of both infestation sites fall partly within Switzerland, the infestations are also monitored there. Since the beginning of 2019, both areas have been considered extinct.

In early August 2016, a homeowner in Hildrizhausen (Böblingen district) found a beetle in his garden. A search (with sniffer dogs) was launched immediately, and the team found a further 14 beetles and 20 infested trees. The infestation has been considered eradicated since the beginning of 2021.

Another beetle was spotted shortly afterwards, this time in Altdorf (also in the Böblingen district). However, the search there for exit holes, other symptoms of infestation or additional beetles was inconclusive. This beetle may have been brought there in firewood or by a vehicle.

  • Saxony-Anhalt

A bigger ALB infestation was discovered in Magdeburg in 2014. In 2015, sniffer dogs were used there. In 2016, 50 trap trees and 200 pheromone traps were used; these caught another eight beetles. Infested trees have also been detected until 2020. Beetles caught an other infested trees discovered (willow, maple, poplar, few ash trees).

Italy

The Asian longhorned beetle first appeared in Italy in 2007. It was later found in three other regions.

  • Lombardy

In June 2007, the invasive beetle species was discovered in a private garden in Corbetta,  provinz of Milano, where a maple tree and three birches showed signs of infestation. The area was then demarcated and monitored. Traps were also used here. No infested plants have been detected since 2022 and no beetles since 2019. There is also an increased focus on public education.

Two infested maple trees were spotted in Vittuone in March 2010, though no signs of infestation were recorded in 2011 or 2014. The infestation is considered eradicated.

Two infested maple trees were reported in Sedriano in 2013. It is assumed that the infestation was connected to a company that worked with packaging and had previously been located in the area. This outdoor infestation has now also been eradicated after four years of monitoring.

In 2017, another case of ALB infestation was reported from Lombardy, this time in the province of Bergamo. Buffer zones were established in Trescore Balnearioand Zanobbio , taking in several surrounding villages (Gorlago, Entratico, San Paolo d'Argon and Cenate Sotto​​​​​). There are also 9 tree nurseries in the affected area. In addition to visual inspections, varying numbers of traps were set up.  In 2023, 2 ALB were found in traps, and 16 infested trees were discovered. In these cases the tree species were maple, horse chestnut, birch, poplar and willow.

In Ghisalba at the end of July 2021, one beetle was discovered in a public park, and 69 infested trees were found (1 Aesculus (horse chestnut), 68 Acer (sycamore)). In 2022 no beetles were discovered in the six traps, but a further 5 infested trees were found in the area. In 2023, an infested maple was discovered, but no beetles were found in two traps. No infested plants were discovered in nurseries in 2022 and 2023, either.

At the end of May 2022, a beetle and a pupa were discovered in the municipality of Grumello del Monte, as well as 61 infested trees. Traps were also used here. In 2023, a further 6 infested trees were discovered, but no beetles were found in the three hanging traps that had been set.

In Treviolo, a tree with two ALB larvae and traces of feeding was discovered in 2023. The monitoring programme initiated immediately also revealed traces of infestation in the neighbouring village of Curno. A total of 10 infested trees were found (4 Acer platanoides, 4 Acer saccharinum, 2 Betula pendula).

A public information campaign is implemented very year in Milan's airports and trains to raise awareness of the Anoplophora species among travellers.

  • Veneto region

An infested maple tree was spotted in a garden in Cornuda in June 2009. 
An infested group of trees was discovered in Maser (provinz of Treviso) in 2010. 

Since 2014, decreasing numbers of infested trees have been registered. The two infestations were reported as eradicated at the end of 2020.

  • Marche region

Exit holes and egg-laying sites were discovered on a maple tree in a private garden in Grottazzolina, Province Fermo, in August 2013. In addition to other locations, there are also 8 tree nurseries in the area under review.

In 2016, a new ALB infestation was reported from Ostra and the surrounding area in the Province of Ancona.

In July 2019 two new infestations were reported from the Marche region.
Fermo, Province Fermo: beetles and symptoms were found in maple and elm.
Civitanova, Province Macerata: 6 infected maples, 3 infected horse chestnut trees and 1 infected poplar and 1 infected elm each as well as adult beetles.

A new Infestation was reported in March 2020 from the province of Fermo in Sant'Elpidioa. 11 elms were affected. The source of the infestation is still unknown..

  • Piedmont region

In 2018, two new outdoor infestations were discovered in Piedmont:
In July, in Vaie (province of Turin), two infested maple trees were spotted in an urban park, 34 maples along a road, as well as one willow. Beetles, larvae, eggs and excursion holes were found on the two 12-metre-high park trees, and mainly egg deposits on the other, smaller trees. Phytosanitary measures were implemented immediately. Insecticides were also used.

In September 2018, 87 infested maple trees, 3 birchand 1 horse chestnut were discovered in Cuneo (province of Cuneo). Here, too, phytosanitary measures were taken immediately. In both cases, the path of introduction is unknown.

Belgium - eradicated

In 2008 2 beetles were found in a private garden. Probably they were brought in with packaging wood from Chinese stone goods. Since 2011 this infestation is considered to have been eradicated.

The Netherlands - eradicated

Sightings of the Asian longhorned beetle have been reported in two Dutch provinces. Both infestations have now been eradicated.

  • Province of Flevoland

The first outbreak of this pest in the Netherlands was discovered in Almere in 2010, which was an unusual infestation owing to the fact that both living and dead beetles as well as larvae were found in an industrial park, but there were no eggs. Some exit holes were presumably around three years old by the time they were detected. The infestation has been eradicated in 2011.

  • Gelderland province

Another infestation site was discovered in 2012 in Winterswijk and some of the exit holes there were also three years old. Four years later (2016), this infestation has been reported as eradicated.

Switzerland

Sightings of ALBs have been reported in three Swiss cantons. Three infestation sites have been eradicated. In the meantime, all this infestations have been eradicated in minimal time.
In 2022, a new outdoor infestation was reported from Zell, Canton Lucerne. Control measures are underway.

 

  • Canton of Fribourg

Switzerland’s first outbreak was recorded in 2011 in Brünisried. This site was peculiar, owing to the fact that no exit holes were found despite intensive searching. It came to light in 2014 that this outdoor infestation was caused by the shipment of infested firewood from Marly (Fribourg), which was only discovered in 2014.
This discovery made it clear that, in addition to checking potentially infested trees, stores of firewood should be monitored.
At the Brünisried site, it emerged that, owing to the relatively high altitude and the associated shorter vegetation period, the ALB's development cycle could last three years, resulting in dissipated development.
In 2012, neither beetles nor symptoms were found in Brünisried. However, in 2013, beetles, larvae and exit holes were spotted once again. At that point, similar control measures to those used in the infested area in Winterthur were implemented. After four infestation-free years, the outdoor infestation in Brünisried – Switzerland's first – has been considered eradicated since late 2017.

The large infestation site in Marly with two focus zones has also been considered to be eradicated since late 2018 - in a minimum time of only four years.

  • Canton of Zurich

An outdoor beetle infestation was discovered in 2012 in Winterthur. A row of maples was infested, as were numerous trees from the nearby industrial park and residential area. Around 140 exiting beetles were spotted, as were many larvae, pupae, egg-laying sites, exit holes and signs of maturation feeding. Most of the exiting beetles at both Marly and Winterthur could be caught upon discovery of the infestation. The Marly infestation was unusual in that most of the beetles had yellow markings. This is the only time to date that this marking pattern has been spotted in Europe.
Since winter 2016, after four years without infestation, one infestation site is considered to be eradicted. This shows that it is quite possible to eradicate even a large infestation within four years.

  • Canton of Aargau

A further outdoor infestation was reported in Berikon in September 2015. Once again, most of the beetles sighted were flying out from a maple tree. Some of the beetles had somewhat sparse markings, so at first sight they appeared almost black. This field infestation could also be reported as eradicated in the minimum time of 4 years at the end of 2019.

  • Canton Lucerne

In August 2022, a suspicious case of ALB reported by an attentive garden owner in Zell was confirmed. The canton immediately took the necessary measures. Numerous beetles, larvae, egg depositions and escape holes were recorded during the monitoring carried out by arborists and sniffer dog teams.

ALB

Fig. 6 - In Marly (Switzerland) is the only site in Europe where beetles with yellow markings were discovered alongside beetles with the usual white ones. You can find additiona information about the Asian longhorned beetle on the WSL’s information sheet (in German). Photo: Doris Hölling (WSL)

ALB

Fig. 7 -  Some of the beetles in Berikon have somewhat sparse markings and appear almost black when first seen. Photo: Doris Hölling (WSL)

UK - eradicated

The quarantine pest was sighted for the first time in the UK in 2011 close to Paddock Wood, Kent, where over 200 living larvae were discovered. Since 2019, this field infestation has been deemed to have been eradicated.

Finland - eradicated

Finland’s first outdoor infestation of ALBs was spotted in October 2015, when two beetles were found on the pavement by an employee of a stone importing company in Vantaa, Southern Finland close to Helsinki. Further investigations carried out in the surrounding area identified suspicious signs, such as egg-laying sites in birch and willow trees. Once these trees had been felled, larvae and one beetle that was ready to hatch could be seen. It is assumed that the quarantine pest arrived at the company’s site in wooden packaging. Investigation at this site included visual inspections, sniffer dogs and pheromone traps. After 5 years of intensive monitoring, this outdoor infestation is considered eradicated in 2020.

Montenegro - eradicated

The first outdoor infestation was spotted in October 2015, on a willow in Budva. Its origin is unknown. Control measures were taken immediately and have remained negative. Since September 2020 this infestation is considered to be eradicated.

Poland

In 2003 an infestation of a private bonsai was reported from Poland. However, this report is unclear.

Lebanon

An ALB infestation was also reported from the city of Aabrine in northern Lebanon. Two beetles were discovered there in 2015, another animal in 2016. It is possible that the introduction took place with packaging wood material.

Merkblatt: Invasive Laubholz-Bockkäfer aus Asien

Ein Merkblatt der Forschungsanstalt WSL dokumentiert Lebensweise und Bedeutung des Asiatischen Laubholzbockkäfers (Anoplophora glabripennis) und des Chinesischen Laubholzbockkäfers (Anoplophora chinensis). Es fasst die Verwechslungsmöglichkeiten mit einheimischen Arten zusammen und zeigt mögliche Bekämpfungsmassnahmen auf.

Download Merkblatt (PDF)