Bees prefer nectar with small amounts of nicotine and caffeine over nectar that does not comprise these substances at all, a study from the University of Haifa reveals. "This could be an evolutionary development intended, as in humans, to make the bee addicted," states Prof. Ido Izhaki, one of the researchers who conducted the study.
It also turns out that caffeine is a pretty toxic substance. If it were labeled as a pesticide by EPA, it would fall into category 2, carrying a signal word "Warning" based on its LD 50.
If you want to learn more about pesticides, bees, toxicity, etc., come to the March 25 workshop, Can I Wash Dishes With Insecticidal Soap?