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Ips subelongatus (larch bark beetle)


  • Last modified
  • 27 February 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Ips subelongatus
  • Preferred Common Name
  • larch bark beetle
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta

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Ips subelongatus (larch bark beetle); adult. Museum set specimen. Collecting location Russia, Primorskiy Krai.
CaptionIps subelongatus (larch bark beetle); adult. Museum set specimen. Collecting location Russia, Primorskiy Krai.
Copyright©PaDIL/Sarah McCaffrey/Museum Victoria - CC BY 3.0 AU
Ips subelongatus (larch bark beetle); adult. Museum set specimen. Collecting location Russia, Primorskiy Krai.
AdultIps subelongatus (larch bark beetle); adult. Museum set specimen. Collecting location Russia, Primorskiy Krai.©PaDIL/Sarah McCaffrey/Museum Victoria - CC BY 3.0 AU


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Preferred Scientific Name

  • Ips subelongatus (Motschulsky, 1860)

Preferred Common Name

  • larch bark beetle

Other Scientific Names

  • Ips fallax Eggers, 1915

International Common Names

  • English: oblong bark beetle
  • Russian: bol'shoi listvennichn'iy koroed; prodolgovatyi koroed

Local Common Names

  • Germany: Borkenkäfer, Osteuropäischer Lärchen-
  • Japan: Karamashiyashibakikuimushi

EPPO code

  • IPSXFA (Ips subelongatus)

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Coleoptera
  •                         Family: Scolytidae
  •                             Genus: Ips
  •                                 Species: Ips subelongatus

Notes on Taxonomy and Nomenclature

Top of page In Europe, a similar species Ips cembrae occurs on Larix decidua and other hosts. Many authors regard I. subelongatus as a subspecies of I. cembrae. With respect to the whole Eurasian region covered by EPPO, these two taxa are regarded as presenting distinct phytosanitary risks (whether considered as two distinct species, or as subspecies of a single species). With respect to other continents, they can be considered together.


Top of page Egg

No information available.

Typical Ips larva; see Kalina (1969).


The beetle has an elongated body, 4.5-6.0 mm long. It is brown or dark brown and covered with thick, long, yellow-grey hairs. Frons is covered with small grains, which change into dots on the vertex. Prothorax is not narrower than the elytra. The elytra are about one fifth longer than they are wide. The first half is covered with small denticles, the back half is covered with small dots. There are thick hairs on the front part and sides of the pronotum. The hairs are thin or absent in the middle of the back side. There is no middle strip along the back side of the pronotum. Elytra are characterized by parallel side edges. Their width is equal to the space between the base of the pronotum and the upper edge of the cavity situated on the slope of the elytra (area of thick hairs). Intervals between striae are wide and covered with a number of small thin dots and unclear cross-wrinkles. Sides of elytra and edges of the cavity on their posterior slope are covered with thick long hairs. Hairs of the front and middle parts of elytra are thinner and form small rows on intervals. The cavity is bright and covered with small dots and hairs. There are two hardly visible and isolated small rows formed by hairs close to the suture within the cavity. During the life of the beetles, hairs situated on the cavity break off. There are four well-developed teeth on the edges of each side of the cavity. They are situated the same distance from each other. The third tooth is larger than the others (Stark, 1952).

I. subelongatus is variable morphologically. It is possible to find specimens in the same stand that differ in the length and width ratio of the elytra, in degree of hairiness, in size, and also in the location and number of teeth situated on cavity edges of elytra.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


ChinaRestricted distributionCABI/EPPO, 2008; EPPO, 2014
-BeijingPresentEPPO, 2014
-HebeiPresentEPPO, 2014
-HeilongjiangPresentNative Not invasive Zhang et al., 1992; CABI/EPPO, 2008; EPPO, 2014
-JilinPresentNative Not invasive Gao et al., 2000; CABI/EPPO, 2008; EPPO, 2014
-LiaoningPresentCABI/EPPO, 2008; EPPO, 2014
-Nei MengguPresentCABI/EPPO, 2008; EPPO, 2014
-ShanxiPresentEPPO, 2014
-XinjiangPresentEPPO, 2014
-YunnanPresentEPPO, 2014
JapanWidespreadCABI/EPPO, 2008; EPPO, 2014
-HokkaidoWidespreadNative Not invasive CABI/EPPO, 2008; EPPO, 2014
-HonshuWidespreadNative Not invasive CABI/EPPO, 2008; EPPO, 2014
Korea, DPRPresentNative Not invasive CABI/EPPO, 2008; EPPO, 2014
Korea, Republic ofPresentNative Not invasive CABI/EPPO, 2008; EPPO, 2014
MongoliaPresentCABI/EPPO, 2008; EPPO, 2014


EstoniaAbsent, intercepted onlyEPPO, 2014
FinlandAbsent, intercepted onlyCABI/EPPO, 2008; EPPO, 2014
Russian FederationRestricted distributionCABI/EPPO, 2008; EPPO, 2014
-Eastern SiberiaWidespreadCABI/EPPO, 2008; EPPO, 2014
-Northern RussiaRestricted distributionCABI/EPPO, 2008; EPPO, 2014
-Russian Far EastWidespreadCABI/EPPO, 2008; EPPO, 2014
-Western SiberiaWidespreadCABI/EPPO, 2008; EPPO, 2014

Risk of Introduction

Top of page Ips subelongatus is not explicitly regulated by the European Union (EU, 2000). There is, however, ambiguity about its phytosanitary status, since it is considered by some authors to form part of I. cembrae, which is regulated. Besides, I. subelongatus is virtually (except for a small area in northeastern European Russia) a member of the category "non-European Scolytidae", which is also regulated. In practice, it would be logical to consider that the same risk applies as for I. cembrae., or possibly even more, since the central European larch forests, where I. cembrae occurs, face an additional risk from I. subelongatus. In general, I. subelongatus is reported to be rather more damaging to the local Larix species in Asia than I. cembrae is in Europe.

I. subelongatus also presents a risk to other continents where Larix plantations are exploited, particularly North America.

Phytosanitary Measures

Appropriate measures would be to require treatment (debarking or kiln-drying) or "pest-free area" for wood, and treatment or "pest-free area" for bark. For plants for planting, which present little risk, only very large plants (above 3 m) might considered ("pest-free place of production"). It may be appropriate to extend the requirement to other, less important hosts (Picea, Pinus).

Fumigation schedules for sulfuryl fluoride and phosphine have been worked out in Japan (Soma et al., 1998). Methyl isothiocyanate has also been tested (Naito et al., 1999).

Hosts/Species Affected

Top of page Larix spp. are the main hosts. The beetle may also occasionally breed in species of the genera Pinus, Picea, Abies and other coniferous trees.

Host Plants and Other Plants Affected

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Plant nameFamilyContext
Abies (firs)PinaceaeMain
Larix (larches)PinaceaeMain
Larix gmelinii (Dahurian larch)PinaceaeMain
Larix kaempferi (Japanese larch)PinaceaeMain
Larix sibirica (Siberian larch)PinaceaeMain
Picea (spruces)PinaceaeMain
Pinus (pines)PinaceaeMain
Pinus koraiensis (fruit pine)PinaceaeOther
Pinus sibirica (Siberian stone pine)PinaceaeOther
Pinus sylvestris (Scots pine)PinaceaeOther

Growth Stages

Top of page Flowering stage, Fruiting stage, Post-harvest, Vegetative growing stage


Top of page Typical symptoms are: flow of resin coming from the places where attempts have been made to lay eggs, species-diagnostic gallery systems with a central chamber and radial larval galleries, sparse tree crown with partly dead tops and branches. The leaves of attacked trees often show yellowing and wilting.

List of Symptoms/Signs

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SignLife StagesType


yellowed or dead
internal feeding
internal feeding

Biology and Ecology

Top of page I. subelongatus is common in stands of different density and species composition but only if they include larch species. It is not found in pine forests and dark coniferous forests. However, it can invade every coniferous species in stands which include larch species. Sometimes during outbreaks, beetles go up to bare mountainous areas. They can reach 2000 m above sea level. I. subelongatus is the most numerous in larch stands which are characterized by a large volume of impaired and dying trees (in areas of mass reproduction of primary pests, in burnt-out forests etc.), as well as on cutting areas and timber yards (in the presence of freshly felled larch trees). Quite often during outbreak I. subelongatus invades fully sound trees of every age.

When attcking impaired but viable trees, I. subelongatus invades the middle and apical parts of the stem first. For larch trees that are dying it prefers to invade the lower stem, which retains the sappy bast for the longest time.

Beetles start to leave winter asylums in the middle of May. Their mass emergence takes place either at the end of this month or in the first 10 days of June. Mass emergence does not exceed three to five days, although some specimens fly to the end of June. The first copulation cells appear at the end of May, the first gallery systems with finished female galleries appear at the beginning of June.

The gallery system of I. subelongatus resembles that of I. sexdentalis, but is smaller in size. Usually, three maternal galleries extend away from the copulation cell in the longitudinal direction. Two of them go in the same direction (up or down).

It is sometimes possible to find gallery systems with two or four maternal galleries. The length of the maternal galleries is usually 13-17 cm, but they sometimes exceed 25 cm.

Females gnaw egg notches on each side of the gallery. They can make over 50 notches in one gallery. Females do not lay eggs in every notch, and a number of the eggs perish; this is why the number of egg notches does not always agree with the number of larval galleries. Nevertheless the number of larval galleries can be very large, so they get entangled or run into a common weaving cavity at a short distance from the female gallery. Isolated larval galleries do not normally exceed 5 cm. Their width close to the egg notch is around 0.7-1.2 mm. Their width at the end part is around 2.5-6 mm.

The first larvae appear in galleries at the end of May. The first pupae appear in the last 10 days of June; the first young beetles appear in pupa cradles at the beginning of July. The second oviposition of hibernated beetles takes place in the first half of July. Then some females of a new second generation start to lay eggs. Pupae of the summer oviposition are found until the beginning of September. I. subelongatus apparently hibernates in the Baikal region and Kazakhstan in the imago stage (Kostin, 1964). In some northern areas of the Amur Region some of the larvae hibernate (Isaev, 1963; Utkin, 1963). In Central Yakutia young beetles which emerged at the end of July or at the beginning of August start to make maternal galleries and lay single eggs. However, emerged larvae perish in the winter (Petrenko, 1965).

Additional feeding by young beetles occurs in places of their development or in isolated single or group galleries. They are found on tops and branches of dead or dying trees, as well as on stems of young growth. These feeding galleries created by the young adult beetles are 3-7 cm long. They extend away from the common entry like a fan, are crowded and almost always penetrate the alburnum.

Some of the adults hibernate in pupa cradles or in the adult feeding galleries. In most cases hibernation takes place in forest litter under the moss cover 4-5 cm thick and in soil (Florov, 1949). Hibernating beetles are found in the soil at the end of August, although at the same time pupae can still be found in the tree.

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Aprostrocetus blastophagusi Parasite Larvae
Bacillus thuringiensis thuringiensis Pathogen
Beauveria bassiana Pathogen
Cryptaphelenchus diversispicularis Parasite Russia; Russian Far East Larix
Eurytoma xinganensis Parasite Larvae
Tomicobia seitneri Parasite Larvae

Means of Movement and Dispersal

Top of page The natural spread of the pest by adult flight is limited. Dispersal over longer distances depends on transportation under the bark of logs. I. subelongatus has been detected on wood imported into Finland from Russia (Siitonen, 1990).

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Land vehicles Yes
Containers and packaging - wood Yes
Plants or parts of plants Yes

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Bark adults; eggs; larvae; pupae Yes Pest or symptoms usually visible to the naked eye
Stems (above ground)/Shoots/Trunks/Branches adults; eggs; larvae; pupae Yes Pest or symptoms usually visible to the naked eye
Plant parts not known to carry the pest in trade/transport
Fruits (inc. pods)
Growing medium accompanying plants
Seedlings/Micropropagated plants
True seeds (inc. grain)

Wood Packaging

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Wood Packaging liable to carry the pest in trade/transportTimber typeUsed as packing
Solid wood packing material with bark Yes

Impact Summary

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Animal/plant collections None
Animal/plant products None
Biodiversity (generally) None
Crop production None
Environment (generally) None
Fisheries / aquaculture None
Forestry production Negative
Human health None
Livestock production None
Native fauna None
Native flora None
Rare/protected species None
Tourism None
Trade/international relations None
Transport/travel None


Top of page In the greater part of its range in Asia, I. subelongatus infests weakened but live Larix trees mainly in the median and apical parts of the trunk. In wind-blown and recently felled trees, it infests the entire trunk. It has an importance similar to that of Ips typographus on Picea. This species prefers to attack mature trees and, even in cases when it does not kill them, the infestation results in significant decrease of wood and seed production as well as reduction in wood marketability. The most severe damage is usually observed in larch forests previously attacked by Dendrolimus sibiricus, Xylotrechus altaicus and other pests or damaged by forest fires, and are very often followed by outbreaks of other wood borers (scolytids, cerambycids and others), particularly, Scolytus morawitzi, Monochamus galloprovincialis, Melanophila guttulata (Issaev, 1966; Yu et al., 1984; Maslov, 1988; Shamaev, 1994; Vorontsov, 1995).

In Japan (Yamaoka et al., 1998) I. subelongatus has been shown to be associated with several ophiostomatoid fungi, of which Ceratocystis laricicola can weaken and kill larch trees, as in the case of I. cembrae (Redfern et al., 1987).

Similarities to Other Species/Conditions

Top of page I. subelongatus is very similar to I. cembrae, but the range of the two species does not overlap.

Prevention and Control

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Control measures include forest management and sanitation: improving the resistance of forests, cutting and elimination of infested trees. Insecticides such as phoxim can be applied to felled "trap trees" on which the beetles have aggregated.


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CABI/EPPO, 2008. Ips subelongatus. [Distribution map]. Distribution Maps of Plant Pests, June. Wallingford, UK: CABI, Map 706.

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EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization.

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Gao CQ, Ren XG, Wang DS, Zhang HY, Sun SH, Sun JB, Niu YZ, 1998. Occurrence, regulation and forecasting technique of Ips subelongatus. Journal of Northeast Forestry University, 16:24-28.

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