Ruguloscolytus amygdali

Ruguloscolytus amygdali De Geer

(Sometimes placed in the genera Scolytus or Eccoptogaster)

Taxonomic position: Insecta, Holometabola, Coleoptera, Scolytidae.

Common name: Almond bark beetle, shot-hole bark beetle.

Geographic distribution: The Mediterranean region, Southern Europe, India.

Morphology: Body of adult 2-3 mm long; the pronotum is dark with small rounded, longitudinally aligned punctuations, and it overhangs the head. Elytra pale-brown with darker spots. Larva apodous, white-yellow with a brown head, up to 3.5 mm in length.

Host plants: Rosaceous fruit trees, especially stone fruits, like almond and plum and some pome fruits, like apple.

Life history: The adults emerge from their pupal chambers and search for young shoots, in which they dig galleries, feed and mate. The beetles then burrow longer galleries for their reproduction, usually in weakened, stressed or broken branches. They lay single eggs (about 30-50/female) in small galleries that extend from the main gallery, sealing them with a plugs. There are 3-4 annual generations, their populations peak in spring and autumn and they usually live for 4-6 weeks or more. These beetles disperse by flight and their activity is almost continuous, due to overlapping of generations and to the availability of suitable, stressed trees..

Economic importance: This beetle attacks mostly weakened, stressed trees. Its extensive burrowing causes branch weakening and when the stem is girdled, death of trees. In spring buds may also be damaged. The beetle cannot develop in healthy trees due to the extensive gum that flows from the gnawing wounds. Young trees may also be infested, resulting in damaged buds.


Monitoring: Periodical examination of weakened trees or those that show numerous small circular exit holes or bud mortality, accompanied by gum flow. The bark of infested shoots becomes darker and they may die. Special attention should be paid to crop trees standing near attacked orchards or natural host tree stands. The aggregation hormone of the beetle is used for monitoring.

Horticultural methods: Horticultural practices that maintain tree health. Removal of weakened trees and of affected branches, which should be burned.

Plant resistance or tolerance: Pome fruit trees (like apples) are relatively less susceptible, whereas quince and loquat are resistant.

Biological control: Several pteromalid parasitoids attack the pest. The more common are Cerocephala eccoptogastri Masi, Rhaphitelus maculatus Walker, and the bethylids Cephalonomia spp. being the more common. Another parasitoid is the mite Pyemotes sp., which attacks the larvae of R. amygdali along as well as its associated parasitoids. Some strains of the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. Killed >80% of a pest population infesting peach trees. Another entomopathogenic fungus, Aspergilus sp., killed all exposed larvae and adults within 24 hours.


Batta, Y.A. 2007. Biocontrol of almond bark beetle (Scolytus amygdali Geurin-Meneville, Coleoptera: Scolytidae) using Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes). Journal of Appled Microbiology 103: 1406-1414.

Ben-Yehuda, S., (and 5 co-authors). 2002. Aggregation pheromone of the almond bark beetle Scolytus amygdali (Coleoptera: Scolytidae). IOBC-WPRS Bulletin 25 (9): 259-270.

El-latif, A.N.A., Nadia, A., Solaiman R.H.A. and El-Gayed A.A. 2009. Ecological and biological studies on some parasitoid species associated with Scolytus amygdali Guer. (Coleoptera: Scolytidae) in Fayoum Governorate, Egypt. Egyptian Journal of Pest Control 19: 1-4.

Kinawy, M.M., Tadors, A.W., and Abdallah, F.F. 1991. On the biology of the shot-hole bark beetle Scolytus amygdali Guer. (Coleoptera: Scolytidae) on pear trees in Egypt. Bulletin of Faculty of Agriculture-University of Cairo 42: 119-128.

Mendel, Z., Ben-Yehuda, S., Marcus, R. and Nestel, D., 1997. Distribution and extent of damage by Scolytus spp. to stone and pome fruit orchards in Israel. Insect Science and its Application 17: 175-181.

Youssef, N.A., Mostafa, F.F.M., Okil, A.A.M. and Ali, H.R. 2006. Laboratory studies on shot-hole borer, Scolytus amygdali, Guer. attacking apricot trees and its associated parasitoids at El-Fayoum Governate. Annals of Agricultural Science, Ain Shams University Cairo 51: 523-530.

Youssef, N.A., Mostafa, F.F., Okil, A.M., and Khalil, H.R. 2006. Seasonal flight activity of Scolytus amygdali Guer on apricot trees by using traps logs at Fayoum Governorate. Fayoum Journal of Agricultural Research and Development. 12: 186-191.

Zeiri, A., Braham, M., and Braham, M. 2013. Parasitoids of the almond bark beetle Scolytus amygdali in Tunisia. Tunisian Journal of Plant Protection 8: 45-56.

Zeiri, A., Ayberk, H., Mejda, D., Braham, M., Braham, M., 2014. Pathogenic fungus against the almond bark beetle Scolytus amygdali Geurin-Meneville (Coleoptera: Curculionidae: Scolytinae): Aspergillus sp. Egyptian Journal of Biological Pest Control 24: 71-74.

Zada, A., Ben-Yehuda, S., Dunkelbum, E., Harel, M., Assael, F. and Mendel, Z. 2004. Synthesis and biological activity of four stereoisomers of 4-Methyl-3-Heptanol: main component of the aggregation pheromone of Scolytus amygdali. Journal of Chemical Ecology 30: 631–641.