For quite some time researchers have been trying to identify the factors responsible for butterfly declines across the United States.  Recently The Wildlife Society reported that a group of researchers analyzed 17 years of data relating to the impact of land use, climate, and pesticide application on butterfly populations in 81 counties located in five Midwestern states.  The study was undertaken in hopes of identifying the major factors affecting butterfly populations in the region.

       The results of the study (recently published in PLOS ONE) indicate that, out of all of the factors evaluated, insecticide use is the strongest link between both declines in the size of butterfly populations and butterfly diversity.  It has caused and 8% drop in the numbers of butterfly species in the study area.  The researchers went on to say that crop seeds treated with a group of pesticides known, as neonicotinoids appear to have had the largest impact.  They also noted that the monarch butterfly is one of the species that has been negatively impacted by the use of these insecticides.

       Neonicotinoid insecticides are systemic poisons.  In other words, they are absorbed and spread to all parts of a plant including its roots, stems, foliage, flowers, nectar, and pollen.

       This should be concerning to home gardeners as they often use these pesticides in their own gardens.  Ironically, studies have found that pesticides are often applied by homeowners at rates higher than are used in commercial farming operations.  In addition, even if you do not apply pesticides to the plants in your yard, neonicotinoids can be present in the nursery stock you transplant in your gardens.