Sirex longicauda

Taxonomy

Family: Siricidae
Subfamily: Siricinae
Genus: Sirex Linnaeus, 1760
Species: Sirex longicauda Middlekauff, 1948
Common names: none

Background

Sirex longicauda is a western Nearctic species with black body, red legs, and a very long, distinctive ovipositor (Schiff et al. 2012).

Diagnostic characteristics

See Sirex for genus-level diagnostic characteristics.

Females:

Males:

May be confused with

Sirex longicauda females can be distinguished from most Sirex by the long second hind tarsomere and from S. areolatus by the reddish-brown tibiae and tarsi. Males are distinguished by the reddish-brown fore legs and small vertex pits (Schiff et al. 2012).

Morphological and geographical variation

none recorded

Host associations

Sirex species feed on trees of Pinaceae and Cupressaceae. Sirex longicauda is recorded on Pinaceae species Abies concolor (white fir), Abies magnifica (grand fir), Abies balsamea (balsam fir), Abies sp., Pinus albicaulis (whitebark pine), Pinus ponderosa (ponderosa pine), Pinus strobus (eastern white pine), Pinus sp., and Pseudotsuga menziesii (Douglas fir). The majority of specimens reared (96%) have been on Abies spp. (fir) (Schiff et al. 2012).

Life history

Female Sirex harbor symbiotic basidiomycete fungus in abdominal glands called mycangia. During oviposition, the site is inoculated with the fungus, which begins to decompose the surrounding wood. Larvae feed on the fungus, and in the process bore galleries through the wood (Johnson 1930, Schiff et al. 2012).

Larvae are creamy white and grub-like in appearance with a dark head capsule. As with adults, larvae possess a short dorsal horn on the posterior end of the body. The larvae bore galleries into wood, feeding until pupation and subsequent emergence. Throughout this process, the larvae use their horn to pack the tunnel behind them with sawdust. Emergence holes are perfectly circular. The fungal symbiont is carried in specialized organs in female larvae that develop into the mycangia after metamorphosis (Schiff et al. 2012).

The flight period of S. longicauda is from early June to mid-October, with a peak in late September (Schiff et al. 2012).

Distribution

World: North America

North America: Sirex longicauda is mainly a western species with many records from British Columbia, Washington, Oregon, Idaho, Utah, Colorado, California, and New Mexico. There are several specimens farther east that are potentially adventive and brought from the west in lumber (Schiff et al. 2012).

Map data from Washington State Department of Agriculture Entomology Collection.

Details about data used for maps can be found here.

Sirex longicauda female lateral habitus; photo by H. Goulet, CNC

Sirex longicauda female lateral habitus; photo by H. Goulet, CNC

Sirex longicauda female dorsal habitus; photo by J. Orr, WSDA

Sirex longicauda female dorsal habitus; photo by J. Orr, WSDA

Sirex longicauda male lateral habitus; photo by H. Goulet, CNC

Sirex longicauda male lateral habitus; photo by H. Goulet, CNC

Sirex longicauda tarsal pulvillus; photo by H. Goulet, CNC

Sirex longicauda tarsal pulvillus; photo by H. Goulet, CNC

Sirex longicauda tarsus; photo by H. Goulet, CNC

Sirex longicauda tarsus; photo by H. Goulet, CNC

Sirex longicauda ovipositor; photo by H. Goulet, CNC

Sirex longicauda ovipositor; photo by H. Goulet, CNC

Sirex longicauda ovipositor base; photo by H. Goulet, CNC

Sirex longicauda ovipositor base; photo by H. Goulet, CNC