Homeowners in America use an extraordinary amount of pesticide (insecticide, herbicide, and fungicide) on their properties each year. In fact, there are more pesticides (measured in amount of chemical per acre) used in home landscapes than is used in American agriculture. Since pesticides are designed to kill either insects, weeds, or disease, their effect on songbirds is a concern.
Diazinon, the most popular insecticide in home landscapes in America, has been banned from golf courses, athletic fields, and cemeteries because in granular form, it will kill any songbird that ingests it. Diazinon has not been banned from home landscapes, so you should never use the granular form, only the liquid form, if you feel you need to use it at all.
There is little research to determine the effect of other pesticides on songbirds. One particular concern is the potential effect of any “systemic” insecticide. This material is absorbed by the plant and is present throughout the plant’s structure. What has not been studied is whether the nectar of that plant, preferred by honeybees and hummingbirds, has the insecticide in it. Are the seeds, eaten by many songbirds, still containing the systemic chemical? Our advice is to use any pesticide with respect and caution and always use it according to the label’s directions on the container.