image: Larvae of the parasitic nest fly are shown in this photo of a finch nest from the Galapagos Islands. Nest fly larvae attack and can kill the nestlings of medium ground finches, birds made famous in evolutionary studies by Charles Darwin. A University of Utah study found that the finches' immune systems are activated by exposure to the nest fly and to another parasite, the pox virus, raising hope the birds can defeat the alien invaders and survive. view more
Credit: Andrew Hendry, McGill University.