image: Monarch butterflies (Danaus plexippus) cluster on the ground near a wintering site in central Mexico. Monarchs undertake one of the longest distance two-way migrations of any insect species worldwide. They are commonly infected by a debilitating protozoan parasite that can hinder the flight ability of migrating butterflies. This image relates to an article that appeared in the Jan. 21, 2011, issue of Science, published by AAAS. The study, by Dr. Sonia Altizer of the University of Georgia in Athens, Ga., and colleagues was titled, "Animal Migration and Infectious Disease Risk." view more
Credit: N. Kolleda Tarpein