A new study finds that American farmers are using smaller amounts of pesticides, but those chemicals are more toxic and much more harmful to pollinators, aquatic bugs and some plants. Thursday’s study shows that the newer generation of pesticides is not harming birds and mammals nearly as much as in the past because they are aimed more at insects. That means insects near pests farmers want to eradicate are getting hurt more. The study used federal data to show toxicity levels in pollinators and other bugs and plants have more than doubled since 2005.