Sirex woodwasp

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. During oviposition, the female wasp lays two eggs with or without a mucoid substance and a symbiotic fungus for the larvae to feed on once they hatch. The mucoid substance is toxic to trees and aids in tree decline. The ascospores from the symbiotic fungus, Amylostereum areolatum, are also pathogenic. The Sirex woodwasp has a sturdy, cylindrical body without a waist, but with a pointed abdomen. The female body is 15–36 mm (0.59–1.42 in), and the male is 9–32 mm (0.35–1.26 in) long. Both sexes have long, black, bristle-shaped antennae, which are rather close together. The body of the male is black, except for the orange middle part of the abdomen. The wings are yellowish-translucent and the antennae are black. The front pair of legs have a yellowish-orange colour, the back pair is heavily thickened and is coloured black on the posterior splint and tarsus, while the femur is orange. The females are iron blue, and have orange legs and black antennae. This is a notable distinction from Sirex juvencus, which has red antennae. The females also have yellowish wings. The ovipositor is below the tapering tip of the abdomen. The sting is connected with the mycetangia, which are special organs on the abdomen, where the female stores the oidiae (asexual fungus spores), from broken segments of hyphae. These spores are deposited, together with the eggs, in the host tree wood to germinate. Both larvae and adults have strong mandibles and can drill through lead plates. The larvae of the Sirex woodwasp are almost colourless and only have three stub-shaped pairs of sterna. They cut through host wood with their powerful mandibles. They have a pointed, dark tip at their rear end, which presses the drilling dust on the walls of the borehole. They closely resemble other larvae in the genus Sirex.