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.

In case this is not what you’re looking for, we also have in depth articles on:         CICADA KILLERS          DIGGER WASPS          EUROPEAN HORNETS          MUD DAUBERS          WASPS    YELLOW JACKETS



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 get 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 hatch 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!



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.



There are three types of horntail treatments which can be utilized when any local wood is found to have activity. The type of treatment you choose will depend largely on what it is you are looking to accomplish. First, you should do a thorough inspection of all areas where horntail evidence is being found. Be sure to inspect all similar wood types since cross infestations are common. Furthermore, since most infestations actually exist when the wood is used or installed, any part of the structure which was created at the same time as the wood showing evidence is wood that could have activity. 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, since the exit holes are only generated when the adults leave after reaching maturity, larva in the wood feeding and growing can do so with no visible evidence to alert you they are present. 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.

If a 5 yr old house is showing exit holes on the wood used for siding, it is quite possible that larva are 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, it is most likely the problem will 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 have determined if it’s original wood used to build the house or some which was used at a later stage in the houses history, you should be ready to make a decision about what and how to treat.



Solo SprayerBoracareIn the first example above, the home which has activity in the siding should have all the siding treated. This is important because it is quite possible that any one piece of siding could have active larva eating the wood. If left untreated, this wood could sustain enough damage which would require replacement. Since any one piece could have activity, it is a lot less costly to treat all the siding and insure no more damage will occur as opposed to replacing all the wood attempting to remove any activity. The same would apply in the second part of this example where the deck alone was determined to be the source of the infestation. Rather then remove the whole deck, treating it would be a lot less costly, a lot less time consuming and a lot more practical then ripping it down and building a new one. In order to properly treat the siding or deck in this example, you will have to use a product which penetrates the infested wood. BORACARE is such a product. Boracare is a Borate based product which penetrates the wood and then acts as a stomach poison to any wood eating insect. It won’t stop carpenter ants or bees since they don’t actually eat the wood. However, the larva stage of horntails or powder post beetles won’t be able to feed on any wood which is treated. They will quickly die off and the damage being done will cease. Boracare is odorless, can be sprayed on wood both inside and outside homes and lasts for many years. Use one of our SPRAYERS for the application and be sure to get any exposed wood treated. This choice will serve you well providing long term control for any wood eating pest as well as fungus, mold and mildew.

BoracareBoracare:  http://www.bugspraycart.com/insecticide/liquid/boracare-gal

Solo SprayerSolo 454 Sprayer: http://www.bugspraycart.com/equipment/sprayers/solo-1-gallon-sprayer



CrusaderDrione DustUsing the same example above with the deck which was determined to have an infestation that was brought in after the home was constructed, there are two other types of treatments that can be done. The first would be a direct treatment made to any exit holes which are found. This is commonly needed on decks, porches, window frames, and other outside wood which has had some horntail activity. Such wood will tend to attract more activity if left untreated. If you are observing adult horntails entering existing exit holes, there are two direct ways to treat this activity. First, use some DRIONE DUST in the hole. This product is both light and penetrating. It works by dehydrating the wasp and they hate it. Once applied to any one hole, no horntail will enter it again for several months. It is best to treat existing holes using one of our HAND DUSTERS. They have a nozzle which is just the right size for getting the dust into the nest. It will only take 5-10 squirts and most any hole will be thoroughly treated. Let the hole stay open for 3-5 days which will insure any foraging local horntails have time to crawl over the Drione or learn to stay away. Be sure to seal the holes with a wood putty or silicon sealant. This sealing of the holes will allow the application to last a year or more. It is important that a product which lasts this long be used since eggs and larva may not be exposed for year or more. Since Drione is the only dust which will remain active this long, a properly treated hole which is sealed effectively will kill off any eggs or larva which might be in the tunnel.

Drione DustDrione:  http://www.bugspraycart.com/insecticide/dust/drione-dust

CrusaderHand Duster: http://www.bugspraycart.com/equipment/dusters/crusader


D-ForceIf it turns out the wood you are treating will be kept inside, the Drione might be a bit “dusty” and unsightly. For inside applications, use some DFORCE AEROSOL. This comes with a handy straw which will direct the spray straight into the hole. All that is needed is a quick “blast” and you’ll have the chamber saturated. Anything in there will die off immediately and eggs hatching in the future won’t be able to go far without absorbing a lethal dose. Once treated you can seal the hole, paint over it and not have to worry about them returning to use the hole over again.

D-ForceD-Force:  http://www.bugspraycart.com/insecticide/aerosol/d-force-14-oz-aerosol



Hornet KillerUsing the same deck example again, if you have treated it with the Boracare and Drione but are still finding some adult horntails active, you should consider the third treatment option. This is a type of treatment which is direct and designed to deal with the active horntails and will either kill them off or drive them away. The first product to consider is WASP/BEE FREEZE. This is a professional type wasp freeze which works very well at killing horntails on contact. It’s great to have around when you are dealing with them from time to time and just want to kill them quickly so you can go out on your deck with some peace of mind. A squirt with the Wasp Freeze and they will either be killed or will sense the danger and leave.

Hornet KillerBee Hornet Freeze: http://www.bugspraycart.com/insecticide/aerosol/hornet-killer-15-oz


hand held zapperYou might even consider the use of our HAND HELD ZAPPER. This device will effectively electrocute them on contact and though mainly used for moths, mosquitoes, flies, bees and spiders, they work on horntails as well.

hand held zapperHand Held Zapper: http://www.bugspraycart.com/traps/electric/hand-held-zapper


CypermethrinOne last option is to do a broad general spraying which will serve to act as a repellent. CYPERMETHRIN has been proven to discourage carpenter bees, wasps and other nuisance flying pests from landing on treated surfaces and can be applied to any deck or other wood where horntails are active. Just mix some up in one of our sprayers featured above and spray it out over any wood they are targeting. Since horntails don’t like it, they will avoid where it is applied. This will help cut down on seeing them flying around and will generally cause them to go elsewhere.

CypermethrinCypermethrin: http://www.bugspraycart.com/insecticide/liquid/viper-cypermethrin


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 Boracare to treat large amounts of wood which need to be protected from further damage. If you have isolated infestations, use the Drione Dust to treat exit holes and either the Wasp Freeze or the Cypermethrin to keep active adults away and under control. 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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