Sciencemadness Discussion Board

Boric acid as a pesticide

Formatik - 19-5-2008 at 11:35

Found this on wikipedia:
Quote:
Boric acid was first registered in the US as an insecticide in 1948 for control of cockroaches, termites, fire ants, fleas, silverfish, and many other insects.[5] It acts as a stomach poison affecting the insects' metabolism, and the dry powder is abrasive to the insects' exoskeleton.

Boric acid is generally considered to be safe to use in household kitchens to control cockroaches and ants. Homemade ant bait can be made by dissolving 1 teaspoon (5 mL) powdered boric acid and 10 teaspoons (50 mL) sugar into 2 cups (500 mL) of water; this mixture can then be absorbed into cotton balls which are left near ant trails. This reportedly will be carried back into the ants' nest, decimating or even completely wiping out the colony.


I have some H3BO4 around, awesome if this works. :cool:

Fleaker - 19-5-2008 at 11:43

It works for annoying wasps and hornets--I knead the boric acid into honey and leave it in close proximity to where I suspect their hive to be.

Formatik - 19-5-2008 at 11:53

That's an excellent idea.

Klute - 19-5-2008 at 12:55

And it kills bad feet smell too :D

ShadowWarrior4444 - 19-5-2008 at 13:14

As I recall, anti-cockroach pesticide, as sold at generic home centers, is 99% pure boric acid. It is listed as a long-lasting odorless killer of Cockroaches, Ants, Silverfish, Palmetto Bugs, and Waterbugs.

chemrox - 19-5-2008 at 23:59

My impression has been that boric acid works by filling the spiricals and then attacking the exoskelletan as an acid..

MagicJigPipe - 21-5-2008 at 21:48

Boric acid is most certainly an insecticide. In fact, that is how I first heard of it.

I does wonders on roaches. I sprinkled some around my kitchen (in my old apartment) and swept it into all the cracks and crevices. After that I "bombed" the apartment. I never saw another roach. I didn't think it would be that easy.

It is also used in some types of insulation for the same purpose.

Also, I believe it acts as an abrasive, "cutting up" the roach's skeleton/legs.

bio2 - 22-5-2008 at 12:12

Apparently what actually happens is the roaches slowly die of dehydration as the
boric acid crystals lodge in the exoskeletons joints interfering with normal moisture transpiration.

This in the case of the dry dust sprinkled around which seems to be the most effective
treatment. It takes the roaches a couple weeks to die.

Also bait formulas work to some extent, in my experience, as the roaches won't eat the powder.

I used both methods when after a "monsoon" period there was an explosion of roaches in the thatched roof of a house. After about three weeks they were pretty much gone but certainly not totally eliminated.

JohnWW - 22-5-2008 at 15:22

Would aqueous boric acid solution (at its highest concentration) be effective against borers and termites in untreated timber, if the timber was painted or immersed in or sprayed with it? At the same time, fire-resisting chemicals (such as borax, Na2B4O7, and common NaCl), and fungicides such as CuSO4 and Na2CrO4, could be added to the aqueous solution (unless the Cu might be precipitated out as borate).

bio2 - 22-5-2008 at 16:44

It should work if enough can be soaked into the wood and the insects eat it.

Sodium Borate is also used as an ant poison but is not as effective as the boric acid.

Getting the insects to eat the bait may not be as simple as using it added to sugar water. Some ants don't go for sugar syrup so readily.

I used a boric acid, sugar, flour, peanut butter slurry/paste which worked fine for roaches. Try about 20-30% boric acid content.

Xenoid - 22-5-2008 at 18:30

Quote:
Originally posted by JohnWW
Would aqueous boric acid solution (at its highest concentration) be effective against borers and termites in untreated timber....


JohnWW, being a Kiwi, I would have thought you were aware that pinus radiata used for internal timber framing in buildings was treated with boric acid from the 1950's (when rimu started to become scarce) until about 1990. At this time high temperature kiln drying replaced boric treatment - and we all know the consequences of that..... leaky building syndrome! I'm not sure what the current treatment is, probably gone back to high pressure boric acid impregnation, along with the pink dye so you know it's been treated.

pantone159 - 22-5-2008 at 20:30

Quote:
Originally posted by bio2
Try about 20-30% boric acid content.


IIRC, I read several suggestions for ant bait that were more like 2% B(OH)3. Stronger than that, and they didn't bring it back to the nest, which is what does the trick.

I have made one attempt at using this, which didn't really work, but it was strange. I had some ants that were getting into my mouthwash, of all things. I made a cocktail of 2% boric acid in mouthwash, and left it for them. Hardly any took the bait, which indicated failure, but the ants went away anyways.

bio2 - 23-5-2008 at 16:30

That was the strongest I found that roaches would still eat. Five percent also worked.

For ants I use 1-2% NaCN so am not sure how much boric acid they will eat when mixed with bait.

JohnWW - 23-5-2008 at 17:49

Xenoid, - Yes, I am familiar with pressure-boric-treated pine - called H1 grade in New Zealand, which is still made, but it is suitable only for interior framing where there is no contact with water. Tests have found that it is more resistant to fungal attack than kiln-dried pine (which has the worst resistance), macrocarpa, Douglas fir (oregon), kauri, and rimu. But for exterior use, or for interior framing use if greater resistance to possible leakage of water is desired, grade "H3" pine, pressure-treated with copper chromate-arsenate, is needed; and, if there is prolonged contact with water, "H4" is required, in which a greater concentration of copper chromate-arsenate is used. Prolonged contact with soil requires "H5", and "H6" for marine piles, again with higher concentrations of the stuff.

But I was interested in whether milled timber which had been sold untreated, whether kiln-dried or not, could be satisfactorily retro-treated with boric acid, by either painting or spraying or immersion without pressure, and whether other water-soluble chemicals such as copper and chromate salts could be added to the mixture for additional insect and fungal resistance.

There are available in New Zealand "Metallex", which is copper (green) or zinc (clear) naphthenate, made from the naphtha fraction in petroleum refining; and creosote (containing cresols and their derivatives), from the retorting of wood or bituminous coal. These latter are soluble in hydrocarbon solvents such as kerosine and turpentine and waste lube oil, and are more effective than boric acid, but they raise problems of flammability and greater toxicity.

Skrinkle - 23-6-2008 at 13:44

Quote:
Originally posted by bio2
Apparently what actually happens is the roaches slowly die of dehydration as the
boric acid crystals lodge in the exoskeletons joints interfering with normal moisture transpiration.

This in the case of the dry dust sprinkled around which seems to be the most effective
treatment. It takes the roaches a couple weeks to die.

Also bait formulas work to some extent, in my experience, as the roaches won't eat the powder.

I used both methods when after a "monsoon" period there was an explosion of roaches in the thatched roof of a house. After about three weeks they were pretty much gone but certainly not totally eliminated.




Wow, what a horrible and slow demise. :o Is boric acid cheaper and/or slower acting than sodium salicylate? I bet boric acid could be mixed with sawdust to kill termites as I have a terrible termite problem.

Twospoons - 23-6-2008 at 13:56

Beer is probably a better bait for roaches. IIRC old roach traps were meant to be filled with beer, and were designed such that the little buggers would fall in and drown. I can think of a few people who would fall for that sort of trap too :D