California's Bay Area is currently experiencing a significant increase in dragonfly populations, with residents reporting swarms filling the skies. These large insects have been observed in parks, grassy areas, and along waterways throughout the region.
Entomologists refer to the period from June through August as 'peak dragonfly season' in the United States, a time when these insects emerge from their underwater larval stages to become adult flyers. This year, however, the numbers appear to be particularly notable in California. Sightings have been reported near Lake Merritt in Oakland, along the Russian River, and in San Francisco's Dolores Park.
One local observed a marked increase in dragonflies over the past year and a half, stating, "I never ever used to see dragonflies. Since the last maybe year or year and a half there are SO MANY all over the city." Another resident noted their presence in large numbers across various parts of the city, including Washington Square Park and near the Ferry Building.
According to Chris Grinter, senior collection manager of entomology at the California Academy of Sciences, several factors are likely contributing to the high numbers. "Cool weather, wind currents, and an abundance of food (mosquitoes) are likely contributing to the high numbers," Grinter told SFGATE. Dragonflies are voracious predators, with adult dragonflies capable of consuming up to 100 mosquitoes daily. Their larvae also play a role by feeding on mosquito larvae in aquatic environments.
While the swarms might appear unnerving to some, they are considered beneficial for the local environment. Dragonflies are harmless to humans, lacking stingers and venom, and do not perceive people as prey. The insects can reach up to five inches in length with wingspans exceeding six inches, and are capable of flying at speeds up to 35 mph.
Dragonfly activity is not exclusive to California. In July 2024, large swarms were observed along the East Coast in Rhode Island as the insects migrated. Dragonflies typically begin laying eggs in early summer, with eggs hatching within weeks. The nymphs develop underwater through the cooler months, and the next generation of adults emerges in the spring and summer. The period between June and August represents the peak time for observing adult dragonflies as they actively hunt for insects. In the Bay Area alone, researchers identify around 30 different species of dragonflies. Their presence is seen as a natural form of pest control, as they also consume gnats and other flying insects. Dragonflies are able to survive longer in warmer climates, which often extends their active season along the West Coast as summer transitions into autumn.