Flightless Firefly (image) Tufts University Caption Research by Tufts biologists shows that wingless "stay-at-home" female fireflies like that above get less support from their mates than females able to fly. Some species of male fireflies donate a "nuptial gift" to mates -- sperm wrapped in a nutritious high-protein package. But When a firefly species' females lose the ability to fly, the males often evolve to transfer only sperm, with no gift of food. Credit T. Chen Usage Restrictions Use only with appropriate caption and credit. 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.