Ants are common household pests that can be difficult to control. Boric acid is a natural pesticide that can be used to kill ants. But what actually happens when ants ingest boric acid? In summary, when ants eat boric acid, it acts as a stomach poison that causes dehydration and eventually death.
What is Boric Acid?
Boric acid, also known as hydrogen borate, is a chemical compound made up of boron, oxygen, and hydrogen (H3BO3). In nature, it is found in volcanoes, natural hot springs, and oceans. Boric acid powder is white, odorless, and absorbs moisture from the air.
Some key facts about boric acid:
- Low toxicity to humans and pets at low doses
- Used as an insecticide, herbicide, and fungicide
- Kills insects by damaging their exoskeleton, stomach, and nervous system
- Causes death through dehydration in ants and cockroaches
- Naturally occurring mineral powder that can be toxic to insects at small doses
Boric acid has been used as a pesticide since the late 1800s. It is effective against ants, cockroaches, silverfish, and other insects. When applied correctly, boric acid causes no harm to humans or pets.
How Ants Digest Food
To understand how boric acid kills ants, it’s important to know a little bit about ant digestion.
Ants are social insects that work together in colonies. Different types of ants within a colony have specialized roles. Worker ants forage for food, defending ants protect the nest, and other ants care for the larvae.
Ants digest their food in a relatively simple gastrointestinal tract that consists of three main parts:
- A crop where food is stored
- A midgut where food is broken down
- A hindgut where water is absorbed and waste is eliminated
The crop and midgut contain enzymes and acids that digest proteins, fats, and starches. Partially digested food is passed from the midgut to the hindgut. In the hindgut, water and key nutrients are absorbed into the body while solid waste is excreted.
This digestive system allows ants to extract energy and nutrients from the variety of foods they consume, including sweets, grease, bread, fruits, insects, and fungi. The ability of ants to digest so many different foods makes them resilient pests.
Mode of Action of Boric Acid
When ants ingest boric acid, either through grooming or from walking over treated surfaces, the active ingredient accumulates in their body over time. Boric acid is stored in the ant’s crop and midgut.
The acid damages the protective lining of the stomach, causing the following effects:
- Dehydration – Boric acid causes water loss, leading to dryness of the stomach.
- Disrupted digestion – The stomach lining damage interferes with digestion.
- Starvation – Ants are unable to properly digest food for energy.
- Death – Severe dehydration and starvation lead to ant death in 3-10 days.
Boric acid is classified as a stomach poison for insects. It is not a fast-acting poison but rather causes a slow, chronic breakdown of the digestive system.
Behavioral Effects and Symptoms
In addition to physical effects, boric acid also causes changes in ant behavior and symptoms prior to death. Effects include:
- Loss of coordination – Nervous system disruption leads to unsteady movements.
- Reduced foraging – Sickened ants have decreased ability to search for food.
- Lack of grooming – Important sanitary behaviors are abandoned.
- Delayed larval development – Less nourishment provided to developing larvae.
- Colony disruption – Breakdown of division of labor roles.
These symptoms often go unnoticed until large numbers of ants start dying. Boric acid breakdown of social structure and elimination of worker ants ultimately leads to demise of the colony.
Speed of Action
Boric acid does not cause immediate death in ants. It takes 1-2 weeks of accumulated ingestion to produce toxic effects.
There are a few factors that influence the speed of action:
- Dosage – Higher concentrations of boric acid speed up ant mortality.
- Size of ant – Effects are faster in smaller ant species.
- Location – Direct stomach intake speeds up toxicity vs. grooming.
- Temperature – Warmer temperatures increase ant metabolism and boric acid activity.
With optimal conditions of warm weather and direct foraging on high concentrations, worker ants may start dying within 3-5 days. Foraging activity declines noticeably within a week. Complete collapse of a colony can take 2-4 weeks.
Visible Effects of Boric Acid Poisoning
As boric acid accumulates to toxic levels in ants, some visible symptoms appear:
- Lethargy – Ants move slowly and lack coordination.
- Twitching – Leg spasms and tremors indicate nervous system impact.
- Paralysis – Inability to control legs and movement.
- Moribund state – Near death, ants appear motionless and unaware.
- Desiccation – Shriveled, dried bodies due to dehydration.
- Dead ants – High number of ant corpses around nest.
These severe visible impacts occur in the final stages of toxicity just prior to death. The initial breakdown of the digestive tract happens internally before exterior symptoms appear.
Differences From Fast-Acting Pesticides
Unlike fast-acting chemical pesticides, boric acid has delayed effects on ants. Differences include:
- No immediate knockdown – Ants remain active for days after ingestion.
- No excitation phase – Ants do not display hyperactivity, convulsions, or spasms.
- Slower mortality timeline – Toxicity builds up over 1-2 weeks.
- Reduced foraging prior to death – Weakened ants cannot search for food.
- Colony death – Entire nest is eliminated gradually.
The slower action of boric acid is a tradeoff for its safety benefits and targeted effects on insects. It requires more patience than fast-acting chemicals but provides excellent colony control.
Breakdown Within the Ant Colony
Boric acid does not just kill individual ants – it causes a breakdown of the entire colony’s social structure and ability to grow.
Some of the colony-level effects of boric acid poisoning include:
- Declining worker ant population
- Reduced food supplies to larvae
- Smaller colony size over time
- Eventual halt of egg production
- Lack of ants to tend to queen and nest
- Full collapse of colony
As more worker ants ingest the acid while foraging, there are fewer ants left to take care of the queen, larvae, and overall health of the colony. The combination of individual ant mortality and breakdown of social cohesion leads to complete control.
Desiccation of Ant Bodies
One unique effect of boric acid poisoning in ants is desiccation or drying out of bodies.
The dehydration happens through a few mechanisms:
- Water loss through damaged stomach lining
- Inability to absorb water through the digestive tract
- Lack of grooming allows uncontrolled water loss
- Lower humidity levels in dying colonies
Ants have a high surface area to volume ratio. Without proper water regulation, they are prone to desiccation.
As ants die from boric acid, their bodies shrivel up and take on a dried, shrunken appearance. You may see ant legs and wings detached from desiccated bodies. The abundance of dead, dried ants is a clear sign of effective boric acid treatment.
Accumulation in Ant Nests
When applied properly, boric acid persists in ant nests and continuously poisons new generations. Properties that allow buildup include:
- Low volatility – Unlike fumigants, boric acid powder does not easily vaporize.
- Stability – Boric acid remains unchanged chemically over time.
- Lack of breakdown – Ants cannot metabolize or excrete the acid.
- Accumulation in bodies – Passed to new ants through cannibalism.
With regular applications, concentrations inside the nest remain high. New worker ants are poisoned rapidly before they can expand or relocate the colony. This residual activity provides extended control.
Complete Eradication of Colonies
While boric acid takes longer to work, it provides complete control of ant colonies when applied correctly:
- All foraging worker ants are killed off
- No ants left to care for queen, limiting egg production
- Larvae and developing ants are poisoned
- Persistent toxicity prevents reinfestation
- Entire nest population is eliminated
The combined digestive and social effects ensure that all ants in a nest are impacted. Boric acid baits and dusts are designed to maximize intake by multiple generations until the colony is exterminated.
Safety For Humans and Pets
When used properly, boric acid has low toxicity to humans and pets. Safety features include:
- Very small lethal doses for insects vs. mammals
- Low dermal absorption – Cannot penetrate skin well
- Rapid excretion in urine if ingested
- No bioaccumulation in human or animal bodies
- Avoidance of dosages toxic to non-target species
Boric acid has been registered as an insecticide since 1948. Extensive testing has found little mammalian toxicity. Always carefully follow label directions and keep products away from children and pets.
Key Takeaways
In summary, the key effects of boric acid ingestion in ants include:
- Damage to stomach lining, causing dehydration and disruption of digestion
- Behavioral changes like reduced grooming and foraging
- Death of worker ants, leading to breakdown of colony
- Complete control of nests through residual activity and accumulation
- Delayed toxicity over 1-2 weeks, unlike fast-acting pesticides
- Low risk to humans and pets when label directions are followed
Understanding the mode of action, visible symptoms, and timeline of boric acid poisoning in ants can help you use this tool safely and effectively for ant control. With proper application, boric acid can provide thorough elimination of ant colonies in and around the home.