Feb 1, 2012 – Old Home Remedies
QUESTION:
An old timer was asking me about "white washing" barns with lime used for greening up lawns. The question is, does it help with bug control and does it have any effects specifically on termites?
ANSWER:
Isn't it amazing what USED to be done in efforts to prevent or kill pests, and prior to all of our magical synthetic molecules people relied on what Nature provided for them. They long ago made the connection between certain inorganic materials that could be taken from the ground, such as borates and boric acid and calcium oxide (lime), and their ability to kill insects in some manner. Lime is also used in agriculture and even landscaping to raise the soil pH if the soil is too acidic. Acid soils can occur from leaching of other minerals from the soil with irrigation, by excessive use of nitrogen fertilizers, and even the heavy use of mulch and other plant materials to add nutrients to the soil. My father in law grew up in Wisconsin, and he advocated using lime in the garden to "sweeten" the soil, although I never quite knew what that meant.
View past Ask Mr. Pest Control questions.
An old timer was asking me about "white washing" barns with lime used for greening up lawns. The question is, does it help with bug control and does it have any effects specifically on termites?
ANSWER:
Isn't it amazing what USED to be done in efforts to prevent or kill pests, and prior to all of our magical synthetic molecules people relied on what Nature provided for them. They long ago made the connection between certain inorganic materials that could be taken from the ground, such as borates and boric acid and calcium oxide (lime), and their ability to kill insects in some manner. Lime is also used in agriculture and even landscaping to raise the soil pH if the soil is too acidic. Acid soils can occur from leaching of other minerals from the soil with irrigation, by excessive use of nitrogen fertilizers, and even the heavy use of mulch and other plant materials to add nutrients to the soil. My father in law grew up in Wisconsin, and he advocated using lime in the garden to "sweeten" the soil, although I never quite knew what that meant.
Years ago we had a product introduced and then removed from the market, and this contained powdered limestone. It was used as a desiccant much the same as our current silica gel and diatomaceous earth dusts are, so it had the ability to kill insects in that "non-toxic" manner by cutting into their exoskeleton and causing dehydration. It is possible that by painting a thick slurry of the cheap lime over barns and maybe even fencing it could help to keep fly populations down by killing the adult flies that landed on those surfaces. Lime and limestone dust are not, I do not believe, considered to be of any use when ingested by insects, and once the lime gets wet it may lose its desiccant properties. So, for termites the lime is probably not an effective material at this time. Mixed in the soil it is not likely to either repel or kill termites, and on wood the termites may bypass it of put mud over the top of it.
It's always interesting to look for information on the toxicity of such "non-toxic" products, and as luck would have it the internet is filled with good information. For example, the LD-50 for hydrated lime is about 6500 mg/kg, making it only a little less toxic to mammals our Synthetic Pyrethroids, and since lime is used at a very high concentration, while the pyrethroids are diluted hundreds of times for use, it kind of makes that whitewash more hazardous that our "toxic" insecticides.
At this time I do not know of any commercial insecticide products using lime or its derivatives, so just in case he was asking for your approval to once again white wash the barn, I'd stay away from it.
View past Ask Mr. Pest Control questions.
