Wood Wasps/Horntails

Horntail Wasp Facts

Horntail wasps or wood wasps are known for their wood-boring nesting behavior. One of the largest concerns related to these wasps are their tendency to burrow into the wood of trees, but often go unnoticed. This means that occasionally timber is harvested with the larvae of these wasps still developing inside. Some cases have been reported of developing wasps emerging from processed wood used in buildings or homes. These insects can be found all across the U.S. but a larger number of subspecies can be found in California, Oregon, and Washington.

Horntail Wasp Stings

Horntail wasps are related to wasps but do not have the ability to sting or bite. The biggest thing to worry about with these potential pests, are the unsightly holes they can leave in the wood of your home.

Horntail Wasp Infestation

Unlike most wasps, the horntail wasps do not construct a nest in the ground or attach one to high terraces. Instead, this species finds decaying, weakened tree trunks or timber, and injects their eggs directly into the wood. Included with the eggs is a fungus used to break down and soften the wood for the larvae to eat. The eggs will hatch, and the larvae will begin to eat its way up through some of the softer wood, and then return back down to feed on timber deeper into the trunk. The feeding and nesting process can take up to a year’s time, and as such it may be difficult to tell that there are horntail wasps nesting in your yard or home. While many wasps develop from their egg stages using a host spider or caterpillar, this species has instead evolved to consume softer wood just below the bark of a tree. It typically begins consuming the fungus-ridden wood around their immediate area, then progress upwards eating the soft sapwood of trees just until the bark. Then it returns down again to finish feeding and development. One variation of the horntail wasp, the European wood wasp, was recently introduced to the east coast of the United States. It is important that this species resides stateside because they choose not dead timber, but live tree specimens to lay their eggs in. This increases the likelihood of the eggs remaining in wood used to make high quality lumber for commercial use.

Types of Horntail Wasps

Horntail Wasp Identification

Commonly described as: wood wasps.

In terms of color it can be difficult to use a single descriptor, since the term “wood wasp” is used to describe a number of subspecies. The appearance can vary from blue to black or even red/brown. Their markings are typically red amber or yellow, and they usually have a thicker waist than most wasps. Ironically despite the non-stinging nature of these wasps, the females often look the most intimidating of all the species. This is because of their large ovipositor, an appendage used only for laying and placing eggs (it can sometimes be longer than their body). While sharp and seemingly dangerous, these ovipositors cannot be used to sting humans, so concern is minimized. The majority of these types of wasps are approximately one inch in size — although the females may be much longer due to their ovipositor.

Horntail Wasps In The Garden & The House

Wood wasps search for timber that is infected or already decaying, there is little danger of them nesting in the processed hardwood found in commercial building or homes. If the wood in which they nest is processed to create planks, palates, or low grade sheets of wood it is possible that they may emerge later in their life cycle resulting in horntail wasps inside your home. The number of wasps per individual nest is relatively small, as they do not live in a colony. This is fortunate because if timber infested with horntail wasps was used in your home, even when emerging from the wood the wasps will be relatively small in number. More importantly these wasps are not aggressive, and therefore don’t pose too much of a threat to humans. Horntail wasp damage doesn’t weaken the structural integrity of the wood, but can create a number of aesthetically displeasing holes.