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Showing posts with label boric acid. Show all posts
Showing posts with label boric acid. Show all posts

A couple years ago I posted some thoughts on dealing with invasive ants in the garden and provided a recipe for homemade liquid ant poison (see The Uncarved Block - Ants!). My DIY ant poison has been successful, but, I have found liquid poison to be somewhat inconvenient – it is clumsy to distribute and goes bad quickly. Thinking back to my youth, I recalled how accidentally dropping a piece of candy would attract ants like crazy. So, I decided to try and make ant poison “gumdrops.” I have been experimenting with various formulations. This posting is a work in progress. I am having good results, but I’m still fine-tuning the proportions. Friends of mine have asked me for the recipe, so I decided to post it here. If you find it valuable, I would love to hear feedback which could help with improving these “gumdrops”.

I started with a recipe that I found online for gumdrops intended for human enjoyment. I removed all the niceties of a gumdrop that people might like to eat - flavorings, colorings, and attractive shapes. I also skipped any steps required to produce a pleasant texture in the mouth. All I cared about was creating a glob of stuff that is convenient to distribute, that ants will want to eat, and which contains a substance that will subsequently kill them.

The first batch I made was very soft and melted in the sun. In fact, while working in the garden, my original tray of “gumdrops” all melted together into a pool of liquid. They re-solidified when I brought them back inside, but still, I wasn't looking for a “melts-in-your-mouth” texture. I turned to my trusty copy of Harold McGee’s On Food and Cooking: The Science and Lore of the Kitchen, to learn about candies and jellies. From that reading I decided to add pectin and corn syrup. The next batch with these modifications was firmer and much more heat resistant.

When making gumdrops, the outside will be sticky and gooey, so the final step is to roll them in sugar. When I made my first batch I was concerned that a child or animal might find them and eat them. Borax is supposed to be basically harmless to mammals*, but, I wasn't 100% confident about that, and anyway, I wanted the gumdrops to stay where I put them so they would be eaten by ants, not by wayward kids. I figured that a sand coating would dissuade even the most intrepid sugar-fiend. Unfortunately, sand isn't as effective for this purpose as sugar, since sugar absorbs water while sand doesn’t. Coating the “gumdrops” in sugar draws out some of the water, making them firmer and making the coating stick better. Also, I didn't like dealing with the sand; somehow I ended up with sand everywhere. Like going to the beach, sand find its way into everything.

* According to Wikipedia, "...boric acid is poisonous if taken internally or inhaled in large quantities...5 to 20 g/kg has produced death in adult humans." The 3 tablespoons of boric acid in the recipe below weighs about 30g, so, eating the entire batch (yuck) shouldn't harm an adult. The Wikipedia article goes on to say that according to the ADTSR, "...the minimal lethal dose of ingested boron (as boric acid) was reported to be 2–3 g in infants, 5–6 g in children, and 15–20 g in adults."  However, in reading the ADTSR report, I was unable to find those numbers. I suspect they may refer to long-term exposure. I would be eager to hear if anyone has any additional information on boric acid toxicology.

For the next batch I decided to have faith that the average child has better sense than to eat random gobs of goo lying on the ground. I also trusted in the claims of borax safety. This time I dredged the “gumdrops” in sugar. Ultimately I have chosen to store them in a plastic container filled with sugar to keep them dry and separated. This is working well. So far the “gumdrops” are staying solid and dry and none of the pieces that I have distributed have disappeared (other than through the slow chewing of ants.) Note however that if you have children or pets, you may want to use sand or dirt regardless of the benefits of a sugar coating.



Lastly, I have been playing around with the amount of borax in the mix. Ant poison is tricky - one wants to have the ants bring the poison back to the nest before dying, but, the poison must ultimately achieve a lethal dose. Too poisonous and the ants just eat and die. A few hundred dead ants is nothing to an Argentine ant colony. Too little poison and you are just giving the colony a sugary treat. The original liquid recipe called for approximately 16 parts water to 8 parts sugar to 1 part boric acid. I assumed that for a non-liquid approach the water was effectively irrelevant; what was important was the sugar to borax ratio of 8:1, or 2 tablespoons borax to 1 cup sugar. With this ratio it seemed like it was taking weeks for the ants disappear. I guessed that it takes ants much longer to eat a gumdrop and carry the pieces back to the nest than to simply suck up liquid poison. Since then I have kicked up the ratio to 8:1.5, or 3 tablespoons borax to 1 cup sugar. The ants are disappearing much faster now – hopefully the colonies are dying as well. If you try this recipe, please let me know how it works for you.

Please note: I am not a doctor, chemist, nor entomologist. The recipe I’m providing here is based upon my reading and experiences in my own yard, not on formal training. If you choose to make and use either of my ant poison recipes, you do so at your own risk. I provide no warranties either for safety or efficacy.


Ingredients
  • Gelatin Mixture
    • 1 envelope plain gelatin
    • About 3.5 Tbs cold water (Just under 1/4 cup)

  • Sugar Mixture
    • 1/2 cup boiling water
    • 7/8 cups sugar
    • 1 Tbs corn syrup (light Karo)
    • ½ Tbs pectin
    • 3 Tbs borax*

  • About 1/8 cup ice cubes
  • Sugar (or Sand) for finishing gumdrops
* For borax, almost any roach powder should do. They are usually 99% boric acid in some formulation or other. I am using a product called "Hot Shot MaxAttrax Roach Killing Powder" which I get at Home Depot for about $5 a pound. One pound of boric acid lasts years when diluted to ant-poison levels. Note too that companies label their boric acid under a variety of names: borax, orthoboric acid, Trihydroxidoboron, etc.

Method

Pour the cold water into a bowl. Sprinkle evenly with the gelatin and allow it to “bloom” while you prepare the sugar mixture.

In another bowl, mix the ingredients for the sugar mixture. Make sure the sugar and pectin are fully dissolved. If not, microwave for a minute and stir until dissolved. [Note: this is simplified from making confections for humans where proper boiling of the sugar mixture matters.]

Add the hot sugar mixture into the gelatin mixture. Stir until the gelatin is completely dissolved.

Add the ice cubes to aid in cooling. For a delicious gumdrop you wouldn’t want to do this – you would let the jelly solidify slowly. But, for ant poison there is no point wasting time. Allow to cool completely and become firm.

Carve out blobs of gelatin with a spoon and dredge in sugar (or sand if you are concerned about the gumdrops looking too tempting.) Store in a container until ready to use. For the first few days I leave the container open so some water can evaporate, then I seal it to keep them “fresh.” Note: may melt if place in hot location. If so, allow it to re-cool and reform “gumdrops.”




Here in California we have a really problematic little invasive ant called the Argentine ant (Linepithema humile.) They are real pain in the ass. They look quite similar to what we used to call "sweet and grease ants" when I was a kid back in Boston. But as far as I can tell these little invaders from Argentina are nothing but six-legged sweet tooths – grease doesn’t interest them. There are a variety of interests that are concerned about Argentine ants for a number of important reasons – most notably they drive out native species, thereby unraveling an important part of the natural ecosystems. My concerns are much more prosaic: they are major herders of aphids and scale, and, given the opportunity, they get into my kitchen and start going after anything sticky and sweet.

[For those of you that don't know this, many species of ants actively herd various pests that feed on the sap of plants. Insects such as aphids and scale exude a sweet "honeydew" from their abdomens. The ants feed on this, and will protect and defend their herd against predators. They will even move their wards from plant to plant to maximize their yield. Co-evolution. Go figure.]

I have been battling the Argentine ants in my yard for a couple of years now as part of the overall “low-impact” effort to deal with infestations of aphids and scale on my plants. As needed I would go to the hardware store and buy some ant traps of one type or another to put around the affected plants. They seemed somewhat effective, but not 100%. I assume that this is because controlling ants in the great outdoors without a significant broadcast of very nasty chemicals is basically impossible. But, these little traps did assist in managing the pest problem.

A couple of months ago some of these little bastards found a way into my kitchen for the first time [though technically they aren’t “bastards,” they are “bitches,” since all worker ants are female.] I gotta tell ya, when Argentine ants find something they like their numbers are astonishing. I decided it was time to research ant traps further. Around here the most common brand of ant trap is "Grants." Their tagline is, "Grants! Kills! Ants!" As far as I could tell, with Argentine ants, the Grants motto ought to be "Grants! Thrills! Ants!" Other ant traps sold in my area are branded Raid, TAT, Combat, and Terro. I wanted to see if I could figure out which of the different active ingredients in these offerings would best.

Terro ant traps contain a sucrose solution and Borax (boric acid.) Pretty straightforward. Boric acid acts on ants as a metabolic poison. In larger animals it is basically safe and has been used for ages as an antiseptic, antibacterial, and fungicide for humans. It is only harmful if ingested in very large quantities, or administered in small quantities over a long period of time. If you’re looking for something to off your rich uncle, this aint it.

Grants’ active ingredient is Hydramethylnon, a metabolic inhibitor which is claimed to work against Argentine ants, but either it doesn’t, or the bait component isn’t attractive to Argentine ants.

Raid traps contain Abamectin, a nerve toxin which, though naturally derived from bacteria, is pretty nasty stuff. The small quantities in an ant trap are unlikely to cause harm to a large mammal, but with my lovely dog around, I’m not interested.

TAT traps contain Baygon (Methylcarbamate). Baygon is an Acetylcholinesterase inhibitor – again, a nerve poison. As with Abamectin, a large mammal would have to consume a big dose of Baygon to be harmed, but…

Finally, Combat traps use Fipronil. Fipronil is yet another nerve toxin, attacking the central nervous systems of insects. However, it is also the active ingredient in “Frontline,” the anti-flea medication that I already use on my dog. Apparently Fipronil does not affect mammals, because it acts on a nerve receptor that does not exist in mammals (whew.)

OK, that’s was a really long preamble…

Based on my research, the only two ant traps I was willing to touch were Terro and Combat, which, interestingly, were the two that I had found most effective against Argentine ants in my yard (go figure!) But here’s the thing; all of these traps, safe or not, end up being pretty expensive if you are using a lot of them, and I have an endless supply of Argentine ants.

In the course of all this study I kept running into pages on the web describing homemade ant baits. It turns out that boric acid, aka Borax, the primary ingredient in Terro ant traps, is also the primary ingredient in many roach poisons. It is relatively benign, has been around in use for a very long time, and is really cheap. There are two main differences between Borax-based ant traps and Borax-based roach poison. With roaches you just want the insect die – as fast as possible. So roach poisons tend to be 100% Borax powder. You sprinkle it around where the roaches travel, they walk through it, and drop dead. Ant traps contain both Borax and bait. You need to attract the ants to the Borax. Even more importantly, the Borax is quite dilute. You don't want the ants to die right away – you want them to take the poison and bring it back to the nest where it will be fed to the Queen and to all the developing larvae. 100% Borax, while it will create a satisfying little pile of dead ants, won't ever deal with the actual problem: the nest.

Making homemade ant poison turns out to be very easy and astonishingly cheap. I bought the least expensive bottle of 100% Borax roach poison I could find. It was about four dollars for a 1 pound bottle, which should be enough for the next 30 or 40 years. The formula for the bait is approximately 16 parts water to 8 parts sugar to one part boric acid. For a modest quantity that translates to 1 cup water, ½ cup sugar, and 1 tablespoon Borax. It’s easiest to mix if the water is hot.

For outdoor use I got a (non-medical) utility syringe. I just squirt fresh poison mixture into the old traps once in a while (how’s that for reduce-reuse-recycle!) Inside the house (since I don’t have any kids, cats, or pooka’s hopping about that might get into the stuff,) I put small squares of aluminum foil at the back edges of my counters where the ants are, placing a tablespoon or two of mixture on each one. For two or three days there will be an astonishing army of ants endlessly, tirelessly marching to the pool of bait, drinking, and then leaving. It’s actually fascinating to watch. Furthermore, with this easy access sweet liquid, they leave everything else in my kitchen alone. After about three days suddenly the number of ants goes way, way down. A day or so later there might be one or two ants stumbling around looking confused. I usually put these stragglers out of their misery.

Two days ago a new army of ants arrived in my kitchen, but already this virtually-free mixture is doing its work. Thought I’d pass it on to the rest of you.

Notes:
  • This mixture is not my invention. I take no credit for it – I am just singing its praises. 
  • There are a lot of different recipes online for Borax ant poison. They mostly differ in the concentration of the sugar solution, ranging from 2:1 water to sugar to 1:2. My ants seem delighted with the relatively dilute sugar solution given here. At my home a higher concentration of sugar just wastes sugar and causes the solution to solidify faster.
  • Different types of ants are attracted by different baits. They will also require different amounts of Borax to hit that crucial level that is fatal, but not so deadly that the workers die before bringing the poison back to the nest. You may need to experiment to get the right ratios for the ants in your area.

Bon Appetite!
[Update: I have found the liquid form of my homemade ant poison inconvenient to distribute, so I am now making ant-poison gum drops. Here is my updated recipe.]