A swarm of dragonflies stunned and shocked beachgoers in Rhode Island over the weekend. The dragonflies, relatively large and often beautifully colored insects, descended on Misquamicut State Beach on Saturday. Video of the dragonflies shows beachgoers running for cover and hiding under blankets. People could be heard screaming. It's unclear what prompted the cloud of insects to visit the beach for several minutes and then largely disappear. The common green darner dragonfly, which is found in Rhode Island, breeds in July and August. Dragonflies feed mostly on insects like mosquitos, relying on swiveling head and huge eyes to catch their prey.