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Sirex noctilio

What do they look like?

Sirex woodwasps are 2.5 to 4.0 cm in length. Males are slightly larger than females. They are a dark blue-black color, with black antennae, and transparent, yellowish wings. Males have an orange spot in the middle of the body and have black rear legs, while females have orange legs. (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

Where do they live?

Sirex noctilio, the Sirex woodwasp, is native to Europe, parts of Asia, and northern Africa. It is an invasive species and has invaded 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. The Sirex woodwasp spreads to new areas by being moved in shipments of wood and wood products that contain larvae. ("Invasive Species Compendium", 2014)

What kind of habitat do they need?

Sirex woodwasps live in wooded areas that have many pine trees. The wasps need these trees to lay their eggs in and for their larvae to develop in. (Slippers, et al., 2012)

How do they grow?

Sirex woodwasps go through complete metamorphosis, and have the life stages of egg, larva, pupa, and adult. Eggs are laid in trees and hatch after about 8 days, though it may take longer depending on the temperature. Larvae can be killed if temperatures are too cold or too warm. If temperature and other conditions are not good for development, larvae can enter a state called diapause. During diapause, the larvae do not develop. They stay in this state until conditions get better, and then they begin to develop again. When larvae are developing, they must feed on a fungus (Amylostereum areolatum). They tunnel into the wood of the tree. When the have completed development of the larvae stage, they become pre-pupae for about 4 weeks. The pre-pupae move back toward the surface of the tree. They then become pupae for about a month before emerging from the tree as adults. Males emerge before females. Complete development from egg to adult can take up to 2 years. (Slippers, et al., 2012)

How do they reproduce?

Males and females mate on or near pine trees. Males likely release a chemical called a pheromone that attracts female mates. (Cooperband, 2010; Slippers, et al., 2012)

Before laying her eggs, a female has to find an appropriate tree to lay them in, usually a pine tree. The female has a long projection of the end of her abdomen called an ovipositor. She uses this to drill holes into trees, and then the eggs are laid through the ovipositor into the tree holes. A female can lay 25 to 400 eggs this way, each one in their own hole. The female also puts a fungus (Amylostereum areolatum) into each hole with the eggs. The larvae eat this fungus after they hatch. Eggs that are unfertilized will become males, and eggs that are fertilized will become females. (Cooperband, 2010; Slippers, et al., 2012)

  • Range eggs per season
    25 to 400

Females provide nutrients in the eggs for their young to grow and develop. Females also put a fungus, Amylostereum areolatum, with each egg. The larvae will eat this fungus when they hatch. However, once the eggs are laid, the female does not live much longer and does not provide any more parental care. (Slippers, et al., 2012)

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

How long do they live?

Adult males live for up to 12 days after emerging from pupation, while females live for 4 or 5 days. Their entire life cycle, from egg to death, takes about 12 months on average, but it can take as long as 24 months. (Hajek, 2010; Slippers, et al., 2012)

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

How do they behave?

Scientists think that female Sirex woodwasps choose trees to lay their eggs in based on how healthy the tree is. If the tree is already damaged or diseased, the female may be more likely to pick it for her eggs. When the female lays her egg, along with the fungus Amylostereum areolatum, this causes much more damage to the tree and even death.

During bad weather or environmental conditions, larvae can enter a state called diapause, where they stop developing and wait until a time of better conditions to continue development. Researchers are not sure how they are able to do this, but it is a very effective way of making sure these wasps survive. It is also one of the reasons that these wasps have been transported to so many new habitats and regions around the world. They can enter diapause in wood or wood products which are being shipped other places, and begin developing again when they've entered a new habitat with good conditions. (Slippers, et al., 2012; Slippers, et al., 2012; Slippers, et al., 2012; Slippers, et al., 2012)

How do they communicate with each other?

There is not much known about what senses Sirex woodwasps use to view their environment. They likely use sight and touch, and detect chemicals. To communicate with females, males produce chemicals called pheromones that attract females and let them know when the males are ready to mate. (Slippers, et al., 2012)

What do they eat?

Larvae only eat the fungus Amylostereum areolatum, which the female parent leaves in their tree holes for them. Adult Sirex woodwasps are thought to eat xylem from pine trees, a type of fluid inside plants. In its native habitat, Sirex woodwasps will attack Scots, Maritime, and Austrian pines. In North America, Sirex woodwasps use 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

What eats them and how do they avoid being eaten?

Sirex woodwasps do not have many predators in the areas that they have invaded. Woodpeckers have been known to eat them. Larvae also often get attacked by parasitic wasps and nematodes. (Slippers, et al., 2012)

  • Known Predators

What roles do they have in the ecosystem?

Sirex woodwasps form a relationship with the fungus Amylostereum areolatum. This relationship provides benefits to both the wasps and the fungus. When females lay their eggs in trees, they also leave some fungus with each egg. The larvae eat the fungus when they hatch. The fungus also helps to harm to tree and prevent the tree from fighting back against the wasp eggs and larvae. In return, mucus from the Sirex woodwasp helps the fungus grow.

Sirex woodwasps are prey for woodpeckers and other animals. They are considered an invasive species, which means that they live in areas that they are not originally from. They damage native pine trees, which can cause problems for other animals that need those pine trees. Sirex woodwasps are also attacked by many parasites and parasitoids. These parasites use the body of Sirex woodwasps to lay their eggs in and develop in. The nematode, Deladenus siricidicola, is one such parasite. Along with D. siricidicola, the parasitic wasps Rhyssa sp., Megarhyssa sp., and Ibalia leucospoides, and Schletteriums cintipes are all parasites of the Sirex woodwasp. These wasps are typically hyperparasites, which means that they insert their eggs into the body of Sirex woodwasp larvae, where they hatch and develop, killing the woodwasp. This parasitizes the woodwasp larvae, which is in turn parasitizing the tree. (Collet and Elms, 2009; Hajek, 2010; Slippers, et al., 2012)

Species (or larger taxonomic groups) used as hosts by this species
  • pines, Pinus
Species (or larger taxonomic groups) that are mutualists with this species
  • fungus, Amylostereum areolatum
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

The mucus and fungus that Sirex woodwasps put into tree holes with their eggs kills the pine trees. This causes problems for animals and people that depend on the pine trees, as there have been significant losses of pine trees. People have tried several different methods to control the woodwasp populations and prevent further damages. (Hajek, 2010; Slippers, et al., 2012)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

Researchers are making a piece of medical equipment called a probe based on the ovipositor of the female Sirex woodwasp. The long, flexible structure of the woodwasp ovipositor allows it to penetrate tough substances (trees) with no problem. Researchers are using this idea and transferring it to the design of the probe. The probe would be used during surgery, to take biopsies, insert medication, access tumors, or place devices in the body. ("Research: Mechatronics in Medicine", 2014)

  • Ways that people benefit from these animals:
  • research and education

Are they endangered?

Sirex woodwasps are not an endangered species. Instead, they are an invasive species, and people are trying to control the size of their population. ("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)

Some more information...


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.


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.

University of Michigan Museum of ZoologyNational Science Foundation

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Garrett, A.; K. Price and K. Smith 2014. "Sirex noctilio" (On-line), Animal Diversity Web. Accessed May 18, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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