Sirex noctilio

Geographic Range

Sirex noctilio, the Sirex woodwasp, is native to the Palearctic region, mainly throughout Europe, parts of Asia, and northern Africa. It is an invasive species and has been introduced to many other parts of the world, including Georgia, South Africa, the Canary Islands, Canada, the United States, Russia, Brazil, Chile, Uruguary, Tasmania, Australia, and New Zealand. Sirex noctilio is capable of spreading naturally 30 to 50 km per year. Rapid spreading has been attributed to the movement of wood and wood products containing larvae in a state of diapause. ("Invasive Species Compendium", 2014)


Sirex noctilio inhabits wooded areas, typically dense in Pinus trees. These trees serve as hosts for the oviposition and development of larvae. (Slippers, et al., 2012)

Physical Description

The average length of Sirex noctilio ranges from approximately 2.5 to 4.0 cm. Males are found to be slightly larger than the females. Physical traits include a deep bluish black color, possession of black antennae, and transparent wings with a yellow shade. Males have an orange spot in the middle of their abdomen and black rear legs; females possess legs that are orange. (Slippers, et al., 2012)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • Range length
    2.5 to 4.0 cm
    0.98 to 1.57 in


Larvae are capable of hatching within 8 days; actual time can vary depending on conditions. Extreme cold and warm temperatures can terminate the larval development, leading to death. The larvae are capable of taking on a state of diapause in unfavorable conditions that enable them to complete development when conditions are favorable. Ideal temperature for development is 25 degrees Celsius. Development of the larvae results in consumption of the deposited Amylostereum areolatum fungus within the infested tree. As the larvae develop, they tunnel deeper into the sapwood of the tree in which they were deposited. Upon completion of the larvae stage, a pre-pupal stage migrates closer to the surface of the tree; typically around 5 cm from the bark. The prepupal stage can last 4 weeks, with a pupal stage of almost a month to follow. Males emerge from the tree prior to the female and can be outnumbered 3:1. Complete development can take up to 2 years depending on conditions. It is believed that only one generation of reproduction occurs every year. (Slippers, et al., 2012)


Mating between the male and female takes place at the crown of pine trees, often in the tree where the male has emerged. It is proposed that males release a sex pheromone when the male genitalia is exposed, attracting potential female mates. (Cooperband, 2010; Slippers, et al., 2012)

Prior to oviposition by the female a determination of susceptibility of potential host trees takes place. The ovipositor is a primary reproduction structure of the female, extending from her abdomen and used to drill holes for oviposition in host trees. The eggs are then deposited via her ovipositor one at a time. The total number of eggs deposited can range from 25 to 400. Unfertilized, haploid eggs develop into males. Fertilized, diploid eggs develop into females. The female also deposits the fungus Amylostereum areolatum with the eggs. The larvae eat this fungus upon hatching. (Cooperband, 2010; Slippers, et al., 2012)

  • Range eggs per season
    25 to 400

The adult female is believed to have no interaction with the larvae after oviposition. During oviposition, the adult female deposits mucus along with the fungus, Amylostereum areolatum, which is consumed by the developing larvae. She also provides provisioning in the eggs. (Slippers, et al., 2012)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female


The adult male lives for up to twelve days after emerging from pupation; the typical lifespan for the female is four to five days. Their entire life cycle, from egg to death, typically occurs within 12 months; existence of unfavorable conditions, though, results in an undeveloped embryo taking on a state of diapause. By doing so, the life cycle for a female can be extended up to an additional 24 months. (Hajek, 2010; Slippers, et al., 2012)

  • Range lifespan
    Status: wild
    24 (high) months
  • Average lifespan
    Status: wild
    12 months


Tree susceptibility has been hypothesized to contribute to the female’s choice in host trees for oviposition. Previous damage and disease present in host trees are thought to play a role in selection. Physiologically stressed trees prove to be most susceptible; once infested by S. noctilio and the fungus Amylostereum areolatum they are stressed further to the point of death. While the exact mechanism by which the larvae acquire a state of diapause is unknown, unfavorable climate conditions for development are known to be the cause for this behavior phenomenon. Upon more favorable climate conditions, development of S. noctilio larvae continues. It is this behavior that has resulted in the rapid spread of S. noctilio as an invasive species through transport of infested wood and wood products. (Slippers, et al., 2012)

Communication and Perception

The study of S. noctilio is currently limited to controlling spread and infestation in non-native habitats, so there is little research on their communication and perception channels. They are believed to do so through tactile, chemical, and visual means. Pheromones are also produced by males to attract potential mates. (Slippers, et al., 2012)

Food Habits

Larvae consume only the fungus Amylostereum areolatum, which is deposited within the tree during oviposition by the female. The adult S. noctilio is believed to consume the xylem of the pine trees which they invade. In its native habitat, S. noctilio will attack Scots, Maritime, and Austrian pines. In North America, Sirex noctilio has infested and is believed to consume pine species which include red (P. resionsa), loblolly (P. taeda), slash (P. ellotti), ponderosa (P. ponderosa), lodgepole (P. contorta), and Monterey pine (P. radiate). White pine (P. strobus) are attacked, too, but less preferably. (Slippers, et al., 2012; Thompson, 2013)

  • Plant Foods
  • sap or other plant fluids
  • Other Foods
  • fungus


As an invasive species, Sirex noctilio has few predators in its non-natural habitats. Woodpeckers are known feed on them. Their larvae are also very suseptible to parasitic wasps and nematodes. (Slippers, et al., 2012)

  • Known Predators

Ecosystem Roles

Sirex noctilio has a mutually symbiotic relationship with the fungus Amylostereum areolatum that it deposits along with fertilized eggs in a host tree. The mucus of S. noctilio serves as a stimulant for growth in the fungus Amylostereum areolatum. In turn, A. areolatum helps to overcome natural tree defense mechanisms through infestation while also serving as food for the developing larvae of the S. noctilio. This relationship is one reason why S. noctilio is such an effective invasive species.

In its native habitats, S. noctilio serves as prey for woodpeckers and other animals. Sirex noctilio also serves as host to a variety of parasites and parasitoids. The primary nematode, Deladenus siricidicola, has been used as a biological control agent in non-native habitats with some success. Along with D. siricidicola, the parasitic wasps Rhyssa sp., Megarhyssa sp., and Ibalia leucospoides, and Schletteriums cintipes are all native parasites that have served in different countries as biological control agents. These wasps are typically hyperparasites, and parasitize the larvae of S. noctilio which are in turn parasitizing Pinus trees. (Collet and Elms, 2009; Hajek, 2010; Slippers, et al., 2012)

Species Used as Host
  • pines, Pinus
Mutualist Species
  • fungus, Amylostereum areolatum
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Development of a probe used for medical procedures is currently taking place which mimics the structure of the Sirex noctilio ovipositor. The long, flexible structure of the ovipositor is the inspiration, with two halves that fit together as a zipper would. The structure design allows it to penetrate through substance without rotation and possess a length that is virtually unlimited due to its stability. The goal of this advancement in technology is to create a probe that can be used in clinical applications such as surgery, biopsies, inserting medication, accessing tumors, or placing devices in the body. ("Research: Mechatronics in Medicine", 2014)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

A combination of mucus and the fungus Amylostereum areolatum deposited into host trees during oviposition has the capability of causing death to the host tree. In habitats lacking natural predators, the negative impact of Sirex noctilio has led to it being considered an invasive species. The effect of Sirex noctilio on pines has caused significant pine losses. There have been efforts to manage the S. noctilio population using several methods, including other parasitic wasps as natural biocontrol methods. (Hajek, 2010; Slippers, et al., 2012)

  • Negative Impacts
  • crop pest

Conservation Status

Sirex noctilio has no special conservation status. It is currently recognized as an invasive species in the U.S. by the U.S. Department of Agriculture’s National Invasive Species Information Center. Its first reported U.S. sighting was in 2004, when it was found in New York, and has since been reported in Pennsylvania, Vermont, New Jersey, and New Hampshire, Indiana, Michigan, and Ohio. Efforts to control the population are under way. ("Convention on International Trade of Endangered Species of Wild Fauna and Flora", 2014; "Environmental Conservation System", 2014; "Michigan Natural Features Inventory", 2014; "National Invasive Species Information Center", 2014; "The IUCN Red List of Threatened Species", 2014; Slippers, et al., 2012)

Other Comments

There currently is some debate on the taxonomy of the nematode that serves as an effective predator to the Sirex noctilio. Most refer to the genus Deladenus siricidicola as being accurate; others use the genus Beddingia siricidicola. For the purposes of our research, the more common Deladenus siricidicola has been used. (Slippers, et al., 2012)


Angela Garrett (author), Grand View University, Kelsey Price (author), Grand View University, Kyle Smith (author), Grand View University, Felicitas Avendano (editor), Grand View University, Dan Chibnall (editor), Grand View University, Angela Miner (editor), Animal Diversity Web Staff.



Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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living in the southern part of the New World. In other words, Central and South America.

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living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


union of egg and spermatozoan


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


An animal that eats mainly plants or parts of plants.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body


referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


an animal that mainly eats fungus

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


chemicals released into air or water that are detected by and responded to by other animals of the same species

seasonal breeding

breeding is confined to a particular season


remains in the same area


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.


uses sight to communicate


2014. "Convention on International Trade of Endangered Species of Wild Fauna and Flora" (On-line). Accessed March 11, 2014 at noctilio.

2014. "Environmental Conservation System" (On-line). Accessed March 11, 2014 at

2014. "Invasive Species Compendium" (On-line). Accessed March 24, 2014 at

2014. "Michigan Natural Features Inventory" (On-line). Michigan State University Extension. Accessed March 11, 2014 at

2014. "National Invasive Species Information Center" (On-line). Accessed March 11, 2014 at

2014. "Research: Mechatronics in Medicine" (On-line). Imperial College of London. Accessed April 02, 2014 at ndsteerableprobeforneurosurgery.

2014. "The IUCN Red List of Threatened Species" (On-line). Accessed March 11, 2014 at

Collet, N., S. Elms. 2009. The control of Sirex wood wasp using biological control agents in Victoria, Australia. Agricultural and Forest Entomology, 11/3: 283-294.

Cooperband, M. 2010. "Labratory Observation of Sirex noctilio: Pursuing an Effective Behavior Bioassy" (On-line). Accessed March 13, 2014 at


Slippers, B., P. de Grout, M. Wingfield. 2012. The Sirex Woodwasp and its Fungal Symbiont. New York: Springer.

Thompson, B. 2013. Microbial Symbiotics Shape the Sterol Profile of the Xylem-Feeding Woodwasp, Sirex Noctilio. Journal of Chemical Ecology, no. 1: 129-139.