When a dragonfly larva crawls up out of the water onto emergent vegetation or a rock to split its skin and emerge as a winged adult, it is in its most vulnerable state, for until its wings are pumped up and dry, it is incapable of flying.
Often for two or three hours a newly-emerged dragonfly will cling to the substrate, pumping hemolymph into its wings until they are fully expanded and then hang there defenseless while its exoskeleton and wings begin to harden. Only then does pigment in the dragonfly’s body become apparent, and its formerly pale, colorless head, thorax, abdomen and wings (see inset) assume their true colors.
The pictured Common Grackle has taken advantage of this precarious stage in a dragonfly’s life cycle and collected several dragonflies to feed to its offspring. The dragonflies’ lack of color indicates that this predation took place while the dragonflies were still flightless and before pigmentation was present.
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Dragonfly larvae reside in ponds until the time comes for them to climb up stalks of emergent vegetation or adjacent rocks, split their larval skin and emerge as adults (a process called eclosure). Before it can take flight, a dragonfly has to cling to the substrate long enough to expand its wings by pumping fluid into them, and dry its exoskeleton as well as its wings. During this time the dragonfly is extremely vulnerable – not only can it not fly, but it is usually situated directly above the water. The slightest breeze can blow it from its precarious perch into the water below, where opportunistic predators such as this Eastern Newt are at the ready and make quick work of their helpless prey.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.