Jun 12, 2011 – Why Borates Kill Bugs
QUESTION:
I know that DOT (disodium octaborate tetrahydrate) is extremely effective against urban pests. Why and how does it truly work?
ANSWER:
A quick seminar on borates. The original material is a mineral called Borax, and this is mined from the ground. I don't know if it is still around, but as a kid we used soap called Boraxo, and there were TV ads for "20-Mule Team Borax", depicting long mule trains pulling carts filled with this mined material. Borax is used for many other reasons, but it also is known to be toxic to insects, so it is refined for pest management. One misconception (bald faced lie??) that is spread on the Internet is that borates and boric acid are "non-toxic" to people, and thus are good "alternatives" to those nasty toxic pesticides. This is dangerously false, as borates and boric acid are quite toxic to humans and pets and often used at nearly pure concentration.
The least refined is the Borates, which are essentially borax, composed of sodium, boron, and oxygen. The borax can be highly refined to a crystalline material that we call Boric acid, and it also is known as orthoboric acid, another name for the same thing. The "borates" go by the names Sodium Tetraborate Pentahydrate (Boracide Powder), Sodium Tetraborate Decahydrate (Terro and Intice baits), and Disodium Octaborate Tetrahydrate (Nibor dust, Gourmet baits, BoraCare, Timbor, Borasol, etc.). These are all extremely similar but with slightly varying molecular makeup.
However, in ANY of its refined forms the boric acids and borates are stomach poisons, and they must be ingested to affect an insect. Therefore, those arthropods that do not have the ability to ingest the active ingredient are not going to be killed by boric acid dusts or borates on surfaces, and this includes blood feeders such as bed bugs and mosquitoes, or other insects that feed with a sucking mouth. The exact mechanism by which the borate actually kills the insects seems to be a little unclear, even now after many decades of use of these products for insect control. However, somehow the borate interferes with the proper digestion or metabolism of the food eaten by the insect and eventually the insect, in a sense, starves to death. It is possible that the borate affects microorganisms in the gut of the insect (bacteria and protozoa) that are responsible for helping with the digestion of the insect's food, and in this manner interrupt proper digestion. We know that termites and roaches have these symbiotic colonies of microorganisms in their gut, and that without them they would have difficulty digesting wood and other materials they eat.
I have asked some of our most respected experts whether or not borates also have any desiccant action on insects - in other words, could the dust get onto the exoskeleton of the bug and cause it to dehydrate in the same manner that silica gel and diatomaceous earth dusts do, and the answer has been a firm "No". Boric acid is toxic only if ingested, despite claims you find on the Internet that say otherwise.
If we apply boric acid or borates onto a surface they remain there for many, many years - perhaps forever - because we are essentially applying a mineral that simply does not change over time. The dust formulations need to stay dry in order to impinge on the passing arthropod, but formulations that we can apply to wood such as soluble powders or liquid concentrations will then be effective on any insect that consumes that treated wood, and this will remain effective for a very long time. Many of these spray-applied products, mixed with water, only rest on the surface of the wood, and cannot penetrate into the wood any further than the water will carry it, which may be only a fraction of an inch. Some formulations, such as BoraCare, may have solvents in them that enable the borate to move very deeply into the wood, and this could be a huge advantage in preventing WDO attack on that wood.
The female powderpost beetle deposits her eggs by sliding her ovipositor down into a crevice in the wood, and this may bypass a surface treatment of the borate. But, if the borate has moved deeply into the wood the larva is going to feed in that treated zone at some point, and be killed. Termites that find access to wood by bypassing soil treatments will still end up feeding on borates within the wood. Even fungi will be killed when they feed on borates, so it can be toxic to both plant and animal organisms.
View past Ask Mr. Pest Control questions.
I know that DOT (disodium octaborate tetrahydrate) is extremely effective against urban pests. Why and how does it truly work?
ANSWER:
A quick seminar on borates. The original material is a mineral called Borax, and this is mined from the ground. I don't know if it is still around, but as a kid we used soap called Boraxo, and there were TV ads for "20-Mule Team Borax", depicting long mule trains pulling carts filled with this mined material. Borax is used for many other reasons, but it also is known to be toxic to insects, so it is refined for pest management. One misconception (bald faced lie??) that is spread on the Internet is that borates and boric acid are "non-toxic" to people, and thus are good "alternatives" to those nasty toxic pesticides. This is dangerously false, as borates and boric acid are quite toxic to humans and pets and often used at nearly pure concentration.
The least refined is the Borates, which are essentially borax, composed of sodium, boron, and oxygen. The borax can be highly refined to a crystalline material that we call Boric acid, and it also is known as orthoboric acid, another name for the same thing. The "borates" go by the names Sodium Tetraborate Pentahydrate (Boracide Powder), Sodium Tetraborate Decahydrate (Terro and Intice baits), and Disodium Octaborate Tetrahydrate (Nibor dust, Gourmet baits, BoraCare, Timbor, Borasol, etc.). These are all extremely similar but with slightly varying molecular makeup.
However, in ANY of its refined forms the boric acids and borates are stomach poisons, and they must be ingested to affect an insect. Therefore, those arthropods that do not have the ability to ingest the active ingredient are not going to be killed by boric acid dusts or borates on surfaces, and this includes blood feeders such as bed bugs and mosquitoes, or other insects that feed with a sucking mouth. The exact mechanism by which the borate actually kills the insects seems to be a little unclear, even now after many decades of use of these products for insect control. However, somehow the borate interferes with the proper digestion or metabolism of the food eaten by the insect and eventually the insect, in a sense, starves to death. It is possible that the borate affects microorganisms in the gut of the insect (bacteria and protozoa) that are responsible for helping with the digestion of the insect's food, and in this manner interrupt proper digestion. We know that termites and roaches have these symbiotic colonies of microorganisms in their gut, and that without them they would have difficulty digesting wood and other materials they eat.
I have asked some of our most respected experts whether or not borates also have any desiccant action on insects - in other words, could the dust get onto the exoskeleton of the bug and cause it to dehydrate in the same manner that silica gel and diatomaceous earth dusts do, and the answer has been a firm "No". Boric acid is toxic only if ingested, despite claims you find on the Internet that say otherwise.
If we apply boric acid or borates onto a surface they remain there for many, many years - perhaps forever - because we are essentially applying a mineral that simply does not change over time. The dust formulations need to stay dry in order to impinge on the passing arthropod, but formulations that we can apply to wood such as soluble powders or liquid concentrations will then be effective on any insect that consumes that treated wood, and this will remain effective for a very long time. Many of these spray-applied products, mixed with water, only rest on the surface of the wood, and cannot penetrate into the wood any further than the water will carry it, which may be only a fraction of an inch. Some formulations, such as BoraCare, may have solvents in them that enable the borate to move very deeply into the wood, and this could be a huge advantage in preventing WDO attack on that wood.
The female powderpost beetle deposits her eggs by sliding her ovipositor down into a crevice in the wood, and this may bypass a surface treatment of the borate. But, if the borate has moved deeply into the wood the larva is going to feed in that treated zone at some point, and be killed. Termites that find access to wood by bypassing soil treatments will still end up feeding on borates within the wood. Even fungi will be killed when they feed on borates, so it can be toxic to both plant and animal organisms.
View past Ask Mr. Pest Control questions.
