Certain pesticides are harmful to bees. It is one of the many reasons why everyone must read and follow pesticide label instructions. The Environmental Protection Agency (EPA) requires instructions for protecting bees on the labels of pesticides that are known to be particularly harmful to bees.
When most or all of the bees in a hive are killed by overexposure to a pesticide, the EPA calls that a beekill incident resulting from acute pesticide poisoning. But acute pesticide poisoning of a hive is very different from Colony Collapse Disorder (CCD) and is almost always avoidable.
There have been several incidents of acute poisoning of honey bees covered in the popular media in recent years, and sometimes these incidents are mistakenly associated with CCD. A common element of acute pesticide poisoning of bees is, literally, a pile of dead bees outside the hive entrance. With CCD, there are very few if any dead bees near the hive. Piles of dead bees are an indication that the incident is not colony collapse disorder. Indeed, heavily diseased colonies can also exhibit large numbers of dead bees near the hive.
Even pesticides used correctly can impact colonies in subtler ways, aggravating existing stresses, causing additional tiredness or other effects such as disorientation, inability to return to the hive, and damage to the nervous system. Some chemicals used against pests such as the varroa mite are harmful to bees, causing additional colony damage.
Integrated Pest Management (IPM) solutions offer structure and guidance for managing colonies and their corresponding threats by combining various methods to attenuate the impact of pathogens, and limiting the use of pesticides to extreme cases only.
Xerces Society press release: On June 17, 2013, the largest native bee kill ever recorded occurred in Wilsonville, Oregon. More than 50,000 bumble bees died when 55 blooming linden trees were sprayed with the pesticide dinotefuran (also known as Safari) in a Target parking lot.