Boron as an Insecticide
Boric Acid is an effective slow acting poison of Argentine Ants. The toxicity is caused from the Boron compounds that form. Therefore Borax is an equivalent substitute for Boric acid, but has about 20% more boron per weight (21.5% vs. 17%). That means the solution proposed below will contain slightly higher Boron equivalents than targeted because of the use of Borax. You can follow these links (Boric Acid vs. Borax and Ideal Mixture) which show the comparison testing between boric acid and Borax. Also note that boron is a required nutrient for plant growth, however it is toxic in high concentrations, so it’s best to keep it in your bait traps or away from sensitive plants.
The ideal solution of water, sugar and Borax.
The University of California Riverside has experimented to find the perfect ratios of sugar, water and boric acid (borax). You can read the full report(s) (Boric Acid vs. Borax and Ideal Mixture), or you can take my word for it and follow this simple recipe. The ideal solution will be ~0.5% Boric Acid (or Borax) in 25% sucrose water. (wt:vl) During lab testing it was noted that only the 0.5% Boric Acid solution was able to eliminate the entire colony due to the slowed effects of the poison.
400 ml of water
4-1/4 Tablespoons of sugar (density = 1.59 g/cm3) = 100g
1/4 Teaspoon of Borax (density = 1.73 g/cm3) = 2g
Don’t worry if not all of the Borax or sugar dissolves immediately, just leave the solution overnight and it will finish mixing.
You can read more about these pests in my blog here.