Unusual dragonfly swarms sweep across California after warm spring rains

Dragonfly swarms have been spotted across California following warm spring rains, according to experts. Peter Veilleux, a nursery owner in Oakland, noticed the phenomenon while walking his dog near Lake Merritt in July, spotting up to 100 dragonflies flying together. Dozens of individuals in the San Francisco Bay Area and other parts of California commented on their sightings on social media.

Kathy Biggs, a dragonfly expert and co-author of "Dragonflies of California," explained that the large numbers are likely due to warm monsoon storms that occurred in late spring and early summer. Most of the dragonflies are probably wandering gliders, a highly migratory species that can appear in large numbers when conditions align.

These agile fliers can reach speeds of up to 35 mph (56 kph) and use air pressure changes to travel great distances, effectively "surfing" the monsoon system. Joe Del Bosque, a Fresno County farmer, observed swarms of dragonflies flying 10 to 20 feet (3 to 6 meters) above him earlier this month.