Dragonflies Eating Ant Gasters

On 20 Sep 2014 at about 2 pm I noticed a large aggregation of Anax junius in the yard. There were at least 30 individuals apparently foraging between 1.5 and 20 m above the ground. They were circling around above the driveway and the adjacent yard. There is no aquatic habitat in the vicinity and I took this to be a migratory event and reported it as such to http://www.migratorydragonflypartnership.org. I still think this may be the case. An hour later I noticed winged ants crawling up the edge of the garage, but most of them lacked a gaster. I saw at least 40 individuals and all but a few lacked a gaster. I posted a photo to bugguide (http://bugguide.net/node/view/998944) and almost immediately got a response from John and Jane Balaban that they had seen a similar event. At the same time, I posted the photo to the Hymenopterist's Forum on Facebook and got a response from Bolívar Rafael Garcete Barrett that he had also witnessed such an event (dragonflies eating the gaster of emerging alate ants). Though I didn't witness a predation event directly, I now feel fairly certain that this is what happened. I think a large number of migrating Anax junius found an ant emergence and proceeded to gastrate many of the emerging alates. I haven't identified the ant species yet, but I'm working on it. According to Brendon E. Boudinot at Bugguide (http://bugguide.net/node/view/998944), the ants belong to the genus Crematogaster.

Publicado el 21 de septiembre de 2014 por lfelliott