Given to Fly

Rarely moving from near water, stoneflies (the Plecopterans) are an oft unnoticed order of insects. Stonefly nymphs grow in water of fast flowing streams, although some species can be found in still water. Upon emergence, the adults rarely move from near the waters edge, where they feed little if at all. Adults rest their wings flat over their body or wrapped tightly around it, although some species are wingless. They possess two cerci or tails that arise from the 10th abdominal segment (DeWalt, 2009 Encyclopedia of Inland Waters pp. 415-422).

Stonelfy Adult

Stoneflies don't fly very well. Individuals in flight can often be brought to earth with just a touch. Some don't even engage in proper flight at all, such as the North American species Taeniopteryx burksi which, upon emergence from the water, escapes to the river bank by skimming across the water surface (Marden and Kramer, 1994 Science 266 pp. 427-430). This form of flight does not generate total weight support as contact with the water removes this need. Observance of this mode of flight, as well as that of another stone fly Allocapnia vivipara (which are incapable of flapping, but raise their wings in response to wind and glide across the water; Marden and Kramer, 1995 Nature 377, 332 - 334) has lead Marden and Kramer to a controversial hypothesis on the evolution of flight in insects. They suggest that these modes of “flight” show a pathway for gradual evolution to true flight.