Granulate ambrosia beetle

Native to east Africa and South East Asia, the granulate ambrosia beetle (GAB) is an invasive wood boring ambrosia beetle.

Adult beetles are reddish-brown in colour. They have been recorded in south-eastern Queensland and are considered an aggressive species that may attack stressed trees, freshly cut logs, seedlings and healthy trees. They mainly attack hardwood trees but can also attack conifers.

GAB can cause:

  • wilted foliage and branch/twig dieback that can lead to plant death
  • toothpick-like spikes of frass (compacted sawdust) up to 38mm long extending from the branches
  • pencil-lead sized holes (2mm)
  • fungal staining from ambrosial fungi in wood.

Granulate ambrosia beetle is not a prohibited or restricted invasive animal under the Biosecurity Act 2014.

Scientific name

Xylosandrus crassiusculus

Other names

  • Asian ambrosia beetle

Similar species

  • Black twig borer (Xylosandrus compactus)
  • Black stem borer (Xylosandrus germanus)
  • Thickset scolytid borer (Cnestus solidus)
  • Shot hole borer (Scolytus rugulosus)


  • Adult females are 2–3mm long, reddish-brown in colour with darker rear end.
  • Adult males are 1.5mm long, flightless and do not leave tunnels.
  • Adults have downward facing head completely hidden by the pronotum from the dorsal view.
  • Front portion of head and sloping posterior are dull and grainy in appearance.
  • Long bristles can be seen on the back end of forewings.
  • Larvae are white, legless and C-shaped, with well-developed darker head capsule.


  • GAB attack over 200 species of plants in 41 families, mainly hardwood. Likely that any hardwood tree or sapling can be attacked.
  • Female GAB bore into twigs, branches and trunks and excavate tunnels into the sapwood.
  • They introduce a symbiotic ambrosial fungus into the tunnels.
  • Adults and larvae feed on the ambrosial fungus, not the wood.
  • Females lay eggs in brood chambers and remain with offspring until they mature.
  • Males are rare and cannot fly. They fertilise females before leaving chambers and flying in search of new hosts.
  • Infestation usually occurs on main trunk close to the ground.
  • Can be spread by moving infected branches and stems, timber and packing materials or nursery stock.


  • Recorded in south-eastern Queensland.

Life cycle

  • The life cycle (egg to adult) averages 55 days.
  • Adult activity peaks in spring, remains active at low levels throughout summer and autumn.
  • All life stages can be found together in the galleries during growing season.

Crops affected

  • Avocado, macadamia, mango, pecan, eucalypts, peach, plum, coffee, lychee, persimmon and other fruit and nut trees. It is likely that any broad-leaved tree or sapling can be attacked. Attack in conifers has been reported, albeit rarely.



  • Outbreak could severely affect native trees and forests.


  • Severe outbreak of the pest could significantly impact the employment and livelihood of growers of perennial tree crops, nurseryman, foresters and saw-millers, and the sustainability of these industries.


  • Severe outbreak of the pest could significantly impact the employment and livelihood of growers, and the sustainability of the industry. It could also significantly impact amenity plantings and trees in rural and residential areas.


  • If you see symptoms consistent with granulate ambrosia beetle call the Exotic Plant Pest Hotline on 1800 084 881 or Biosecurity Queensland 13 25 23.

Legal requirements

  • Granulate ambrosia beetle is not a prohibited or restricted invasive animal under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
  • Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.

Further information