There are a great many pesticides and herbicides at use out there, and in many cases, you may not even be aware that a plant, or seed you are purchasing have been treated with something. Many pesticides have been found to be toxic to bees and other pollinators. It is important to understand if you choose to use these chemicals, read the labels or talk to those professionals that are applying them around your property. When necessary, applications of chemicals are best done on days that are calm, either early in the morning, or even better, in the evening, once bees are done foraging for the day. Avoid spraying those foraging plants that the bees are especially paying attention to if at all possible. Also be aware there is a phenomena called “drift” in which pesticides are airborne upon application, and can often cover vegetation that was unintended to be treated.
Bees will travel up to 10 miles in some cases looking for pollen and nectar sources, and when those flowers and trees have been treated, the bees bring these chemicals back to their nests where it can affect many more. Neonicotinoids are a group of pesticides that are incredibly harmful to pollinators, and even birds. These chemicals are taken up into the plant in all its tissues, and can last for long periods of time, making them poisonous to those that come in contact with them much longer than just a few days or weeks.