32.09. Scolytus scolytus (Fabricius, 1775)

Ecology and presence in Slovenia

The species is distributed in Europe, extending north to Sweden, eastern and western Siberia, Kazakhstan, Turkey and Uzbekistan. Siegel (1866) states that the species was “rare in Carniola”. In the 20th century, the species was distributed throughout most of Slovenia, with the exception of the NE. Only two new records are known after 2000 (Figure 165). Populations are probably in decline due to elm dieback. Hosts include Ulmus carpinifolia, U. laevis, U. glabra and Zelkova carpinifolia, less frequently Quercus suber, Fraxinus excelsior, Carpinus betulus, Prunus dulcis, Prunus armeniaca, Populus nigra, Salix nigra and Juglans regia. In Slovenia, the species has been found on Ulmus minor, U. glabra and U. campestris. Monogamous species, develops two generations per year, swarms in May and June. Inhabits the thick-trunked parts of the tree, trunks and thicker branches. The tunnel system is longitudinal, located almost entirely in the bark, the maternal gallery is 2-3 cm long. Adult length is 3.0-6.0 mm. The abdomen rises obliquely from the 2nd sternite towards the elytra, with one small button-shaped bump on the 3rd and 4th sternites. Sexual dimorphism is evident in the shape of the forehead and in the tuft of hairs on the anal sternite (Figure 164). The young beetles perform maturity feeding on leaf petioles and twigs. The species carries spores of the dangerous Dutch elm disease (Ophiostoma ulmi and O. novo-ulmi), making S. scolytus an economically very important species. Pheromones: (+)-threo-4-Methyl-3-heptanol; threo-4-Methyl-3-heptanol and α-Multistriatin (Blight et al. 1977; Gerken 1977).