The Sirex woodwasp (Sirex noctilio) is a species of horntail, native to Europe, Asia, and northern Africa. Adults vary in length from 9 to 36 mm (0.35 to 1.42 in). This woodwasp is an invasive species in many parts of the world, including Australia, New Zealand, North America, South America, and South Africa, where it has become a significant economic pest of pine trees. The wasp can attack a wide variety of pine species, although some species seem to be more susceptible than others, and stressed trees often are attacked.