Wood Wasps, Horntails
Family: Siricidae, Xiphydriidae, Orussidae, Anaxyelidae
There are several kinds of wood boring insects that are identified as wood wasps and horntails.
Wood wasps that are part of the family Siricidae are large non-stinging wasps that are attracted to dead or dying conifer trees.
Infested timber can lead to an infestation in completed buildings.
Wood wasps found in North America are about an inch in length, elongated with a cylindrical body.
They have a black or metallic dark blue body with black, red and yellow stripes and make a noisy buzz when flying.
Larvae are yellowish white with a small spine at the tail end. This spine tail is where they get the name “horntail”.
The female wood wasp is larger than the male with a long egg laying apparatus, or ovipositor, which can exceed her body length.
The apparatus is only used for egg laying and cannot be used to sting in defense.
The adult female wood wasps inserts her ovipositor into the wood of weakened or dying pine, spruce and fir trees and lays one to seven eggs.
After hatching in three to four weeks, the larvae tunnel into the wood, with
their tunnels running parallel to the grain of the wood. As it chews, the larvae use a spine at the tip of its abdomen to help push itself forward through the wood.
It eats the softer wood under the bark, moves to the hardwood within the trunk and returns to the sapwood.
Each tunnel is about ten to twelve inches in length.
The larvae pupate at the end of the tunnel and emerge five to six weeks later as adults, leaving behind an exit hole in the wood.
Unlike carpenter bees and carpenter ants, wood wasps actually eat the wood where they nest.
Woodpeckers and other types of birds hear the larvae moving through the wood. Infestations can identified when
the birds peck away at siding, molding, fascia boards or any part of the structure where young wood wasps
can be found.
Wood wasps cause more cosmetic damage than structural to buildings. Large exit holes can be seen in wall board, plaster walls, hardwood floors, linoleum, carpeting, non ceramic floor tiles and other interior surfaces.
Once infested, the wood wasp does not re-infest a structure.
Wood wasps that are part of the Orussidae family are known as a parasitic wood wasp.
They are identified differently because their ovipositor is folded and looped around its gut and the female eggs are longer than her body.
They lay their eggs in trees and attach to wood boring beetles. Adults are ant-like in appearance and will crawl and hop slowly and jump instead of fly.
Wood wasps in the Anaxyelidae family are known as cedar wood wasps or incense cedar wood wasps.
They lay eggs only in recently burnt incense cedars, red cedars and junipers.
The wood is usually still smoldering when eggs are deposited. They are found from central
California to Southern British Columbia.
Wood wasps that are part of the Xiphydriidae family have a long skinny neck and usually bore into dead wood.
In the fall of 2004, a foreign wood wasp was found in New York. The Sirex, or
European horntail has wiped out 80 percent of trees in New Zealand, Australia, South America and South Africa.
The European wood wasp is sometimes confused with potter wasps and wood wasps native to North America.
They are identified differently by their coloring. The European wood wasp have the same dark metallic blue or black body but instead of stripes, they have an orange segment on their body.
They have reddish yellow legs, black feed, black hind legs and a black antenna.
The European wood wasp attacks scotch and red pine trees. The adult female penetrates live trees and lays between twenty five to two hundred fifty eggs depending on the size of the female.
Once the wasp penetrates the tree and lays its eggs, the tree begins to die.
Along with the eggs, the female disperses a fungus that penetrates the bark of the tree to help the larvae survive.
Once the fungus attacks the tree it takes less than a year for it to die. Infested pine trees are identified by the wilting in the upper branches, discoloration in the pine needles and the beads of resin that trickle down from the holes where eggs are laid.
Management of the wood wasp has been successfully controlled in New Zealand and Australia by the introduction of a parasitic worm that gets into the larvae leaving the eggs infertile.
Scientists are unsure introducing the worm into the United States will be successful because pine trees in the southern US are more diversified and the entire wasp population would become susceptible to the worm and possibly wipe them out.
Thanks to Lani Powell for researching and writing this article!
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