Phloeotrogus crassiusculus Motschulsky, 1866: 403.
Xylosandrus crassiusculus (Motschulsky): Wood 1977: 68.
Xyleborus semiopacus Eichhoff, 1878: 334. Synonymy: Wood 1969: 119.
This species was recorded from Bhutan by Schedl (1975 as Xyleborus semiopacus Eichhoff).
Distribution. The species is native to and widespread through the Oriental region, extending North to Japan and Korea, and East to New Guinea, Fiji and Samoa; presumably originally imported to tropical Africa, but now widespread in the Afrotropical region; imported to and established in southern Europe, Australia and the Americas.
Biology. The species is strongly polyphagous, and numerous host trees are listed by Dole & Cognato (2010). The biology and gallery system have been described by Browne (1961), Schedl (1963) (both as Xyleborus semiopacus), and Ranger et al. (2016) amongst others. This is a species of economic importance because it can attack and breed in healthy shoots and twigs, although it more usually attacks physiologically stressed plants (Ranger et al. 2016). This can facilitate the introduction of pathogenic fungi (Mayers et al. 2016). It has become a major pest species in the southern USA, especially in fruit tree nurseries. Management strategies are discussed by Ranger et al. (2016, 2021), Gugliuzzo et al. (2021), and others.