There are many types of insects which will readily nest or feed in wood. Some of the more common insects include termites, carpenter bees and carpenter ants. There are others which are not as widely known but can do just as much if not more damage. Horntails, also known as Wood Wasps, are such an insect.
HORNTAIL WASP BIOLOGY
Horntails are medium to large sized wasps which live and feed on wood. Unlike Carpenter Bees or Carpenter Ants, Horntails actually eat the very wood in which they nest. Life cycles can take a few years to complete so local infestations are sometimes not noticed until substantial damage has occurred. For this reason, it is important to properly identify and treat local infestations should you suspect you have horntails living on or in any part of your home.
Horntails are active in most parts of the world. They hatch from eggs which are laid in softwood such as pine, spruce or fir. However, in some cases, they can and do thrive on many types of hardwoods. Females lay eggs using their horn like ovipositor. Once they hatch, larva will feed on both the sapwood and heartwood layers of host wood (trees). Though females tend to be attracted to weakened or vulnerable trees, virtually any tree can become a target of their egg laying. Once larva start to eat, they will bore their way through several feet of wood leaving a path of pulpy sawdust or frass in the tunnels they create. This is where all the damage occurs.
Once the larva gets their fill, they will pupate into adults. This cycle can take 1-5 years to complete depending on local temperatures, life cycles and other weather conditions. Once pupa cocoons hatch out to the adult, they will chew their way out of the wood using their strong jaws to get through whatever is in their way. It is not uncommon to find them entering living spaces of homes as they chew their way out. It is also quite common to see them chewing through metal siding, asphalt or any other covering used over wood which is infested. It is at this point when local infestations begin to show themselves; wood which unknowingly has horntail larva or pupa is commonly used for construction since it is hard to detect these young and developing stages. However, once the pupa hatches out adults which exit the wood attempting to mate and lay eggs, it is a lot harder for the populations to remain hidden. In fact, most people notice them right away since the average person is quite frightened of any wasp!
HORNTAIL WASP DAMAGE
Though the adult horntails are quite noticeable and visible, they are not always the first sign which alerts the homeowner that something is active in their structure. Since woodpeckers and other types of birds can “hear” the larva as they work inside infested wood, it is not uncommon for such birds to start pecking away at the siding, molding, facia boards or any part of a structure which is harboring horntails young. They are attempting to harvest the larva, which resemble a large grub, and then consume it for their next meal. It is also quite easy to see the 1/4″ exit holes left by adults as they emerge and leave infested wood. In many cases there will be a series of holes; 10-50 is not uncommon with the average infestation. These holes will be perfectly round and can be observed in just about any type of wood. Siding, overhangs, soffits, decks, door frames, window frames, attics, basements, crawl spaces or porches are some of the more common nest sights but any part of a structure which is wood can be a likely area for an infestation. And though these holes are used as places where the adults are emerging, it is not uncommon to find adult females using these same holes to lay eggs. They do this because instinctively they know this is a fine place for their young to find food and safe harborage. When utilizing old holes for egg laying, you will expect to see adults flying in and out of existing holes as if it was some type of nest. Whether you are seeing active horntails flying in existing holes or if you have located some sections of wood which have horntail exit holes with no visible activity, there are several types of applications that can be made depending on what you are looking to accomplish.
HOW TO TREAT HORNTAIL WASPS IN A HOME
Remember, most horntail wasp infestations actually exist when the wood is harvested. For this reason, it is important to understand that wood which has no evidence does not mean it is insect free. In fact, it could just mean that the larva located in the wood are still growing and feeding and have not emerged yet.
Remember too that exit holes are only generated when adults leave after reaching maturity. For this reason, it is important to consider all areas where specific wood was utilized. Here is an example that will help explain how important such an inspection can be.
Let’s say a 5-year-old house is showing exit holes on the wood used for siding. In this case, it’s entirely possible that larva is active on any side of the home which has the same siding installed.
Contrary to this would be the house that is showing exit holes on a deck which was constructed 1 year after the house was built. If the deck was not a part of the original house, the problem will most likely be limited to the deck alone.
Another example would be if you are finding exit holes in studs or joists in the attic, basement or main area of a house 3-5 years after it was constructed. Such activity would be strong evidence to support that any part of the home could have activity and that the whole structure should be treated. However, if this same house was 10 years old and new activity was being found in wood installed 3 years earlier inside as a molding, it is most likely that the infestation is limited to the wood used for molding only.
These examples illustrate the need to inspect and actively identify just which wood is showing activity. Once you’ve determined if its original wood used to build the house or wood which was used at a later stage in the house’s history, you should be ready to make a decision about what and how to treat.
So, let’s say you have structural wood with horntail activity, you’ll need to treat it with an agent that will penetrate through and through making the wood kill anything trying to eat it. BORATHOR is such a product.
Borathor is a boron-based product which penetrates unfinished wood and then acts as a stomach poison to any wood eating insect. Commonly used for pests like powderpost beetles, it will last for many years, is odorless and works on wood decking, rafters, floor joists and more.
Borathor is thick like corn syrup but mixes with water at the rate 1:1. So one gallon of Borathor will make two gallons of mixed solution and will cover up to 1,000 sq/ft of wood.
HOW TO TREAT HORNTAIL WASPS NESTING IN A TREE
Horntail wasps will readily infest live trees. Their boring young will feed chewing galleries through the trunk which can lead to health problems for the host tree.
If you have horntails emerging from an otherwise healthy tree, you should treat it make sure it stays healthy. Using PROTHOR as a systemic will kill off any type of boring pest like wood wasps and one treatment will last a whole year. It can also be sprayed as a “foliage” or bark treatment.
For long term systemic application, apply 1 oz of Prothor per 10 inches of tree width.
To treat, get a 5-gallon pail and add 3-4 gallons of water. Next, add the 1 of Prothor to the water and use the entire amount by pouring it into holes you make around the trunk of the infested tree. If the tree is 20 inches wide, use two buckets each having 1 oz of Prothor and 3-4 gallons of water.
The holes don’t need to be super deep; 6-10 inches is plenty, but you want them to hold the liquid to keep it in place as you pour it out from the bucket. Keep the holes inside the drip line of the tree and try to stay at least 2 feet away from the main trunk. Use a piece of rebar to make the holes or a pickaxe works well too.
DIRECT TREAT HORNTAIL HOLES WITH FS MP
Now if you’re finding active holes, get them treated with FS MP AEROSOL. Horntails will “reuse” holes and eggs laid deep in these galleries will survive if left untreated.
FS MP uses a unique solvent system that will penetrate deep in the wood killing all stages. Holes will only take a few seconds to treat and ideally, sealing them with any standard wood filler is smart. If you don’t cap them after treating, it’s not easy to tell if new holes are appearing or if the holes are reused in the future. Treatments will last 3-6 months and in general, well treated holes will be ignored. But to eliminate any chance of re-infestation, cap them off.
BEST SPRAY TO PROTECT TREES NOT YET INFESTED
For trees in the yard, you want to protect, spray their bark with MAXXTHOR EC. This spray is highly repellent to horntails and other wood boring insects and will keep them away. Emerging adults from one tree will be looking to either lay eggs on that same tree or any trees close by. But spraying all surrounding trees once a year with Maxxthor will help prevent this from happening.
Mix 1 oz of Maxxthor per gallon of water and plan on spraying as much of the trunk and limbs you can reach.
Though not commonly known as a wood eater, horntails can be a destructive pest if local infestations are left to do as they please. When you find any active in your home, be sure to do a thorough inspection and try to determine how much of the house could possibly have active populations. Use the Borathor to treat large amounts of wood which need to be protected from further damage. If you have isolated infestations, use the FS MP Aerosol to treat exit holes and Maxxthor to keep active adults away and under control. Lastly, for trees or structures where you see them “hanging around” but you’re not sure where they’re nesting, spray Prothor. Its non-repelling, exactly the opposite of the Maxxthor, and as such can control an active nest without you having to know where that nest might be located.
Be sure to monitor wood which has had activity following your applications and retreat as needed. Though easy to control, horntails can be persistent because they tend to appear where you least expect them to be living.
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