The purpose of these articles is to help park visitors notice, learn about and enjoy what's happening outside at Cromwell Valley Park, a beautiful Baltimore County park in Parkville, MD. Many of our topics are suggested by park visitors, so if you have a question, observation or comment, please contact a park naturalist at justine@cromwellvalleypark.org.

Tuesday, June 7, 2011

Tinkerbell at the Pond

Common green darner on iris.  J. Schaeffer
James and Evelyn noticed an amazing event at the pond last week.  They were finding many large dragonfly exoskeletons on the iris, counting almost a dozen.  Finally, hidden among the iris leaves, they found a recently-emerged adult dragonfly--a large common green darner!  We watched several minutes as it quietly readied its wings, then suddenly flew off, with the sun creating sparkling jewels on its new wings--just like Tinkerbell.

Evelyn and James at the pond.
Thanks James and Evelyn for so carefully observing the wildlife at our pond.


Common green darners are among the largest of the dragonflies of our area, having a wingspan up to 4.5 inches.  Their large and complex eyes give them the good vision they need to hunt on the wing, capturing other flying insects like wasps, mosquitoes and other dragonflies.  They live in the water several years as nymphs (immature forms) where they hunt tadpoles and other aquatic insects.  When mature, the large nymphs (about 2" long) crawl up onto the stems of water plants, and emerge as adults from their final nymphal exoskeleton.  While some over-winter as aquatic nymphs, some adults also migrate, using the same migratory routes as song birds and raptors.  In fact, they often become a food item for migrating American kestrels and merlins.