Composition

• Borax and boric acid contain boron, which occurs naturally in most soils. People mine rich deposits of boron and use processing plants to refine it into usable products. Boric acid contains boron, hydrogen and oxygen. Borax, also known as sodium borate, contains boron and salt. The Environmental Protection Agency has approved boric acid and borax salts for use as pesticides, but boric acid is more commonly used to control stinging insects.
  
  

Mode of Action

• Bees and wasps will eat boric acid in sugary bait patties.John Foxx/Stockbyte/Getty Images
  
  Boric acid acts as a pesticide in two ways. The white boric acid crystals scratch the insect's body on contact. The crystals stick to the damaged exoskeleton and pull moisture out of the insect's body until it dies of water loss. When boric acid contaminates insect food stores, they inadvertently eat it. Internally, boric acid causes an electrolyte imbalance, which stops the insect's metabolism from working correctly and results in a slow poisoning.
  
  

Treatment

• Find the bee or wasp nest by carefully following the insects when they return to the nest before dark. Some wasps, including cicada killers, mud daubers and yellow jackets, can build their nests underground. These insects use small holes in the soil to access the nest. Carpenter bees, honeybees and paper wasps often build nests inside wall cavities. Dust the entrance of the nest with boric acid. Sprinkle or blow some inside the nest. Expect to repeat applications over a several-week period, until activity ceases at the nest opening. Always read and follow the manufacturer's instructions when applying a pesticide.
  
  

Post-Treatment

• Once all the bees or wasps in the nest die, fill in or destroy the nest entrances to prevent another infestation the following year. Use spray-in foam to fill wall cavities. Cover holes in the ground with soil. Because honeycomb attracts other pests, always remove it from wall cavities before sealing a nest entrance.