The war on snails continues

More experimenting on snail control.

This paper states

Boric acid (BOA) is currently used as a safe alternative molluscicide to control land snails in sustainable agriculture, but the mechanisms of toxicity have not yet been investigated.

(Boric acid) was found to be lethal against T. pisana with LC₅₀ values of 24.7 and 8.05 mg g⁻¹ (2.5% and 0.8% respectively) after 3 and 7 days of exposure, respectively. BOA sublethal concentrations led to a significant reduction in food consumption and growth of snails after 14 days of exposure...lipid peroxidation level and catalase activity were elevated, whereas acetylcholinesterase activity was inhibited in the treated snails.

Note: Many insecticides are acetylcholinesterase inhibitors. Essentially, it prevents nerve impulses from stopping...muscles lock-up. 

I whipped up a batch of approximately 2.5% bait and... 

They were attracted to the bait but didn't want to eat it.

I am pretty sure my problem is that I didn't use boric acid but substituted the equivalent amount of borax. Borax is a sodium salt of boric acid (commercially available and dirt-cheap). However, it has a pH of about 9 it it appears that snails are sensitive to pH.

Image of the same bait-can on the second morning. It looks like more snails to me.

Another attempt using actual boric acid powder will be attempted in the near future.

Well, alrighty!

Ammonia has a pH of 11(ish) which is 100X more alkaline than borax. Ammonia is expensive and perishable.

Sodium carbonate is cheap (ten cents an ounce) and shelf-stable. A little bit of guessing suggests that a 3% solution of sodium carbonate will have a pH of about 11.8*. So I speedy-quick mixed up 120g of sodium carbonate into 3800ml of water and found some volunteers to test it on.

Solutions with high pH are caustic. Proteins are chains of amino acids that are knit together into tissue. Exposure to high pH solutions shreds those amino-acid chains and dissolves the cell walls of animals like slugs and snails. The reaction is self-limiting. The amino acids that are released lower the pH toward neutral and the reaction fizzles.

Spray that lands on the ground is quickly buffered (neutralized) by the clay-content. Spray that lands on dead grass encounters very little buffering and the dead grass becomes a no-go zone for them until the sodium carbonate is leached out by the rains. 

They did not like the spray. They started falling to the ground about five seconds after getting sprayed.

***Follow-up: I have no evidence that this actually killed the snails. It may have maimed them...but not enough dead-bodies to make any claims. I did a re-spray this morning with a followup a minute later. Many of the snails turn-turtle at the first spray and expose their foot which is a much larger target. 

*Lye and lime have a pH of 14 which is about 200 times more alkaline than sodium carbonate solution