Sirex, You Say!

Contact: Dick Bean, Maryland Department of Agriculture | | 410.841.5920

Sirex, You Say!
Gyorgy Csoka, Hungary Forest Research Institute,

ANNAPOLIS, MD (January 15, 2006) – In February, 2005, a horntail (a wood boring wasp) new to the U.S was discovered by Dr. Richard Hoebeke, in a September, 2004 forest survey trap sample from Fulton, N.Y. Identified as Sirex noctilio, it was not only new to the US, but known to be a serious pest on three other continents. Since 1985, only eight other adult S. noctilio had been intercepted by State and federal inspectors with packing materials from other countries, but subsequent inspections of surrounding areas never yielded further specimens. However, an ongoing delimiting survey of the New York detection has so far turned up 85 adults and larvae from within a 40 mile radius from the initial find.

Ironically this horntail, S. noctilio is not considered a primary pest of pines in its native Europe and Asia, but it has proven to be of major concern in South American pine plantations. It is also established in Australia, South Africa and New Zealand. It therefore should be able to thrive anywhere in North American where there are pine forests. This unusual insect has earned the designation as “Invader of the Month” for January by the Maryland Invasive Species Council.

Although many species of Pine (Pinus) are hosts, Monterey and loblolly appear especially vulnerable. The concern about this wasp is that loblolly and related species of “southern pines” are the bread basket of forestry in southern US. Like many other wood boring insects, S. noctilio tends to favor stressed trees, but it also attacks and kills apparently healthy trees as its populations grow. It has been known to kill up to 80% of the trees in stands of North American pine species grown in plantations in south America. The main reason it is such a threat is because as the female horntail inserts its eggs in trees, it also inoculates the wood with a fungus, Amylostereum aveolatum. As this fungus grows in the wood of the tree it serves as nutritious food for the wasp larvae but it can also rapidly kill the trees. Unfortunately, the lumber salvaged from these dead or damaged trees is often used for packing crates, pallets, and other utility purposes where lumber suitable for furniture or framing would be too costly to use. The slow-growing larvae are difficult to detect before emergence holes appear, and by that time, the crate or pallet may have traveled hundreds or thousands of miles to its destination. Once she emerges, the large female wasp is a strong flyer (as far as 100 miles!), and infestations in other countries expand 5-15 miles per year.

This discovery of an infestation in New York State has federal and State officials concerned and planning to survey more intensively for this exotic pest in other nearby states. Scientists are looking for parasites and predators to combat this serious threat; a parasitic nematode being used in Australia has shown promise. Also, efforts are underway to develop better lures and trapping methods to detect its presence earlier in new infestations. Early detection and intervention is the key to success.

The large “spike-tailed” larvae can mine in wood for more than a year before emerging as a striking 1-1 1/2 inch (25-40) mm long, blue-black, winged adults with orange legs. They do not have a typical wasp’s slender waist. Although there are several other horntails in our area, any suspicious insect should be caught, kept and sent to an entomologist for identification. If you find any insect of concern, contact Dick Bean, entomologist, at the Maryland Department of Agriculture at 410-841-5920.

For more detailed information about Sirex noctilioclick here.

For more information on the Internet:

National Invasive Species Information Center (NISIC)

For more information about other Invasive Species of Concern, visit the Maryland Invasive Species Council.