In early August, my husband and I were on our weekly hike up Mt. Wachusett in Princeton. It was a partly cloudy afternoon and when we reached the summit usual summit breeze was absent. As I looked around, I realized that there were hundreds, no… thousands of large dragonflies darting all around us. Some were skimming along at the level of shrubs and trees, others were easily much higher than the summit fire tower. I had never seen such a sight and tried without luck to photograph them—all I got were black blurs, or gray clouds against the blue sky. The following week, I spoke with one of our Division ecologists about this amazing sight. He told me this activity was called hilltopping and that this is the time of year when large dragonflies such as big darners and emeralds, gather together to make a migratory trip south. I had no idea that dragonflies swarmed and migrated! He said that based on some tagging studies, dragonflies can get as far south as the Carolinas. He also pointed out that the smaller hawks will also follow the swarms to feed on these insects.
I checked in the ever-handy Field Guide to Dragonflies and Damselflies published by our agency to get some more information. I learned that some types of dragonflies are categorized as “spring”, “summer” or “fall” fliers. If you are interested in learning more about dragonflies, particularly identifying them, consider picking up a copy of this guide from the Division of Fisheries and Wildlife. It is the first guide to cover all 166 species found in the Commonwealth, and as the range of many Massachusetts species extends well beyond our borders, will be useful to those interested in dragonflies and damselflies throughout the northeast.
Order a Field Guide from the Natural Heritage and Endangered Species Program.
Field Guide’s co-author, Blair Nikula, kindly permitted us to use this photo of a male Canada Darner, one of the likely dragonfly species we saw swarming on the summit. He recommended the following websites for beginning dragonfly enthusiasts:
Dragonfly information for beginners.
Ecology of dragonflies.
A beginners guide to dragonflies.
@Joe -To address your questions, I took a look at the one of the links on dragonfly information recommended by Blair Nikula. The one recommended for beginners,
http://www.odesforbeginners.com is titled (appropriately) Odes for Beginners. The information is excellent, with a nice dose of humour thrown in as well.
I clicked on the Biology link which explains dragonfly life cycles from the aquatic larval stage to adult dragonfly. It appears that depending on the species, climate and weather, much of a dragonfly’s life is spent as aquatic larvae—in northern climes they can be in the water for months. During that time they shed their skins frequently as they grow.
Once they emerge from the water and shed their final skin, it can take a few days to a few weeks for their body and wings to harden. Adult dragonflies may live a few weeks, in some species, just long enough to fully mature and then reproduce. In some cases, if conditions are favorable, they then enter what is referred to as the post-reproductive period. Based on this information, it’s pretty safe to assume that an adult dragonfly, if migrating, only makes a one-way flight.
Marion
Posted by: Marion Larson | 09/08/2010 at 10:46 AM
Pretty interesting post...how long do dragonfly's live? Do they live to make multiple migrations?
Posted by: Joe | 08/31/2010 at 10:17 AM