Center for Biological Diversity

For Immediate Release, August 20, 2020


Jeff Miller, (510) 499-9185,

Legal Action Seeks Endangered Species Protection for Giant California Fly

Only One Population of San Joaquin Valley Giant Flower-loving Fly Remains

FRESNO, Calif.— The Center for Biological Diversity filed a notice of intent today to sue the U.S. Fish and Wildlife Service for improperly denying Endangered Species Act protection to the critically imperiled San Joaquin Valley giant flower-loving fly.

This hummingbird-like insect has been eliminated from more than 99% of its former range in the San Joaquin Valley. Only one small population remains in sand dunes east of Bakersfield, where it is under immediate threat of extinction from sand mining.

“This unusual dunes insect could be lost forever without the habitat protection and recovery efforts of the Endangered Species Act,” said Jeff Miller, a senior conservation advocate at the Center for Biological Diversity. “How cool is a giant fly that emerges from sand dunes, hovers and accelerates in any direction like a stealth fighter, and only lives for three days as an adult? We need to protect the very last dunes where this unique fly lives.”

The San Joaquin Valley giant flower-loving fly (Rhaphiomidas trochilus) lives in sand dunes with relatively sparse native vegetation. Its known historical range included eight locations throughout the San Joaquin Valley, as far north as Antioch Dunes in Contra Costa County. Much of the flower-loving fly’s historical habitat has been destroyed or degraded by agricultural conversion or by sand mining, which eliminated the Antioch Dunes population.

Other threats to the flower-loving fly include drought effects from climate change, urban and agricultural development, vegetation overgrowth, off-road vehicles and pesticide drift.

The species was believed to be extinct before entomologists discovered two flower-loving fly populations in 1997 near Bakersfield. One population south of Bakersfield was destroyed in 2006 when the land was cleared for agricultural purposes. The only remaining population is at Sand Ridge, a large, stable sand dune east of Bakersfield, in Kern County. Entomologists estimate that the Sand Ridge population has 100 or fewer breeding adults in a given year.

In 2013 Caliente Sand and Mineral Company applied to Kern County to expand sand mining activities at Sand Ridge, prompting two California entomologists to petition for emergency Endangered Species Act protection for the San Joaquin Valley giant flower-loving fly.

The fly was first identified as needing federal protection by the Service in 1991. In 2017 the Service published a briefing paper proposing to list the giant flower-loving fly as a threatened species, but in December 2018 the agency reversed course and issued a finding that formal protection is not warranted.


San Joaquin Valley giant flower-loving fly larvae burrow up to 10 feet deep in moist sands, where they feed on roots of shrubs and prey on larvae of other burrowing insects. Adults are close in size to a small hummingbird, with a 1.5-inch body and long proboscis, or tongue.

Despite their name and unlike other similar species, San Joaquin Valley flower-loving flies do not actually feed on flowers and do not use their proboscis for nectar feeding. Adults are capable of fast and extended flight, covering up to 100 meters in less than six seconds, and can hover like hummingbirds. Adults only live for about three days.

San Joaquin Valley giant flower-loving fly. Photo by Greg Ballmer. Image is available for media use.

The Center for Biological Diversity is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

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