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Ants are everywhere. These insects are admirable for their organized societies but detestable for their invasion of our homes. Ants come into our living spaces looking for food and, once they find it, are difficult to get rid of.
Ant colonies generally contain a queen, other ants, and a brood (eggs, larvae, pupae). The queen is responsible for laying eggs and stays deep within the protection of the nest. The other ants perform specific duties to support the colony. The worker ants are responsible for leaving the nest in search of food and bringing the food back to the colony. Getting rid of an ant colony requires killing all the ants, including the queen and brood.
Methods for dealing with ants generally fall into two categories: repellents and insecticides. Repellents discourage ants from entering a specific area. These products create a barrier that ants do not want to cross; however, they might find another way into the home. Insecticides kill the ants. Insecticides can be found in spray form as well as baits, which also contain ant food. The food attracts ants, and the ants then transport the insecticide-laced food back to the colony. The insecticide is shared with all of the other ants including the queen and brood thereby killing the whole colony. Because of this strategy, ants do not die immediately after encountering the bait since they have to live long enough to return to the colony one or more times to share the poisoned food. When first placed, the bait can initially attract more ants to the area because of the food. Bait manufacturers indicate it can take many days to weeks to see the disappearance of the ants.
Ant baits are available in a variety of forms including liquids, gels, solids, and granules. The liquid and gel baits are available in small bottles, tubes, or prefilled syringes. The liquid is applied to a piece of cardboard and placed in an area where ants are seen. The gels can be placed directly on surfaces and in cracks. Liquid, gel, and solid baits are also available encased in plastic containers that are placed in areas where ants have been seen. These products are sometimes referred to as bait stations and are designed to let ants in but keep children and pets out. Many bait products can be used indoors or outdoors including in food preparation areas; however, some are strictly for outdoor use. Carefully read the ant bait product label and follow the instructions for use.
A variety of insecticides are used in ant baits. The package label will list the exact insecticide under the active ingredients. Common insecticides include sodium tetraborate decahydrate (borax), fipronil, avermectin, indoxacarb, and hydramethylnon. These active ingredients have uses other than as ant baits. Borax is found in some laundry detergents, while fipronil, avermectin, and indoxacarb are used in veterinary medicine to prevent infestation of fleas, ticks and other parasites or to rid an infected animal of these organisms. Borax kills primarily by acting as a stomach poison. Fipronil, avermectin, and indoxacarb poison the ant's nervous system causing paralysis and death. Hydramethylnon interferes with a cell's ability to produce energy. Fortunately, many of these insecticides don't work exactly the same way in humans or are in such low concentrations in the baits as to have low risk for unintentional poisoning.
The toxic effects in humans differ depending on the insecticide. Unintentional ingestion of small amounts of borax can cause nausea, vomiting, abdominal pain, and diarrhea. The vomit and stool can be blue-green in color. Ingestion of larger amounts can cause a red skin rash followed by skin loss as well as seizures and coma. The concentration of borax in many ant baits is only 5.4%, so only small amounts of the active ingredients are present. Fipronil, avermectin, and indoxacarb all have the potential to affect the nervous system in humans. Ingestion of large amounts can cause weakness, tremors, or seizures. Indoxacarb also has the potential to cause methemoglobinemia, which interferes with red blood cells' ability to deliver oxygen to the body. The concentrations of these insecticides in ant baits are generally less than 0.05%. A toddler ingesting the contents of a bait station usually would not get enough insecticide to be dangerous. Finally, hydramethylnon is low in toxicity overall. Ant baits containing hydramethylnon are not expected to cause more than nausea, vomiting, or minor diarrhea if ingested.
The insecticides in ant bait products are not well absorbed across the skin into the body, so getting some on the skin is not expected to cause body-wide effects. However, contact with the skin or eyes can cause irritation.
Ingestion of ant baits should be treated by rinsing out the mouth and drinking a few sips of water. Contact with skin or eyes require rinsing as well.
If you suspect someone has ingested or otherwise been exposed to an ant bait, check the webPOISONCONTROL® online tool for guidance or call Poison Control at 1-800-222-1222.
Karen D. Dominguez, PharmD
Certified Specialist in Poison Information
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