Parasitic Nest Fly Larvae (image) University of Utah Caption 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. Credit Andrew Hendry, McGill University. Usage Restrictions Credit must be given to Andrew Hendry, McGill University. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.