''Sirex juvencus'' is a species of

horntail Horntail or wood wasp are any of the 150 non-social species of the hymenopteran family Siricidae, a type of wood-eating sawfly. The common name "horntail" derives from the stout, spine-like structure at the end of the adult's abdomen, which is u ...

found in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

Sakhalin Island Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh: ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...

and several other countries. Its common name is steely-blue wood wasp because of its color.

Description

Male adults are about long, and female adults are about long. The antennae are red and brown or red and black. They exhibit

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, which means the male and female are morphologically different. The female body has a metallic bluish-black colour with yellowish or reddish legs, and the last part of the abdomen is triangular and wide at the base. The

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

, which deposits the eggs, is as long as the abdomen or a little longer. The eggs are white and elongated, and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e are cylindrical, white, and can measure up to . The male body has a metallic black body, with the first two sets of legs being reddish and the back legs being black. The abdomen is black with bluish-black dots on some parts of the abdomen and brownish dots on other parts.

Reproduction

Adults fly from July to August to mate, and once they have mated, the female will drill several holes in wood and drop one to five eggs into that hole. The female can lay up to 100 eggs. Once the larvae hatch, they feed on the wood, but in the middle of summer they dig deeper into the wood until they are into it. The larvae stay there all winter, and in April, they feed off of sap from the tree. The larvae then make tunnels horizontally that are covered with shredded wood. Before they pupate, they would have made tunnels long where they will stay for the winter. They would finally turn into

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

e in the summer. Once they are adults, they chew through the surface and leave a hole that is in diameter. Most of the time, this species only has one generation every two years.

Impact

''S. juvencus'' is considered a pest because it creates tunnels and holes, devaluing the wood. Mostly, it infests wounded, weakened, or dying wood. This wasp also spreads a symbiotic fungus that attacks wood.

References

National Research Institute of Aquaculture

BioImages - Virtual Fieldguide (UK)
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{{Taxonbar, from=Q374021 Siricidae Insects described in 1758 Taxa named by Carl Linnaeus