What's That Bug? does not endorse extermination

Subject:  Swarming Dragonflies
Location:  Corralitas Red Car Property, Silver Lake, Los Angeles, California
July 15, 2014 10:30 AM
This morning we accepted an invitation to walk the Corralitas Red Car Property with community activist Diane Edwardson and we evaluated the merits of preserving the site as open space.  A large Tarantula Hawk was flying about lazily and then we saw some of the California Harvester Ants that Diane observed swarming about a month ago, but the real treat was seeing a large swarm of Dragonflies circling an endangered California Walnut Tree.  They did not appear to be feeding or mating, and there were at least 50 large Dragonflies in a small bit of air space.   Though we could not get a clear image of a static individual, the large size and overall green coloration has led us to speculate that the Dragonflies are Green Darners.

Swarming Green Darners

Swarming Green Darners

In researching this behavior we learned that the North Carolina Museum of Natural Sciences states:  ” Dragonflies swarm for two reasons.  Dragonflies are predators so if there is abundant food in the area, i.e. lots of small flying insects such as mosquitoes or other flies, a swarm may form in the same area.  In these static swarms, the dragonflies fly back and forth over a specific, well-defined area, eating the small flying insects within that space.  Dragonflies also migrate, so you might see large groups of them flying together in a single direction, either to escape poor local conditions (dry, very hot) or to seek warmer regions in the fall.  Migratory swarms can contain several million dragonflies and travel thousands of miles!”  Though we did not observe any prey, we can only presume that smaller swarming insects were providing food for this magnificent aerial display.  More information on swarming Dragonflies can be found on BayNature.

Swarming Green Darners

Swarming Green Darners


What's That Bug? does not endorse extermination
Location: Silverlake, Los Angeles, California

2 Responses to Swarming Green Darners at Corralitas Red Car Property

  1. Diane E says:

    Hi Daniel,
    I can confirm that indeed those swarms of dragonflies are continuing a few days later, I just wasn’t looking high enough. In the same area above the historic viaduct footings near Fletcher & Riverside, i saw one small swarm above the same tree we observed together on Tuesday. There were two other larger swarms one above a much larger Black Walnut, and one above the huge dead Eucalyptus trees that were recently trimmed – a good 60′ up. As if to confirm the feeding behavior of the Green Darners, my dog snapped at a couple of mosquitoes, I shooed a few off me too.

    There is quite a bit of standing water on Riverside Drive between Fletcher & Glendale Blvd. While it’s great we’ve got natural pest control going on here – people should check their yards for standing water and break the mosquito breeding cycle.

    • bugman says:

      Thanks for the update Diane. Green Darners are one of the species of Dragonflies that migrate, and perhaps this swarming behavior is related to migration as well. According to the Xerces Society: “Dragonfly migration is one of the most fascinating events in the insect world, but also one of the least-known. This is even more surprising when you consider that dragonfly migration occurs on every continent except Antarctica.” According to the Minnesota Dragonfly Society: “Certain species of dragonfly migrate, either en masse or individually. Dragonflies follow weather fronts, fleeing cold fronts in the fall on their way south and chasing warm fronts in the spring when moving north. The best-known migrant is the Common Green Darner, who makes a one-way trip south in the fall and whose offspring makes the return one-way trip north the following spring.”

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