Upper Santa Ana River


Rhaphiomidas terminatus abdominalis

Natural History

The Delhi Sands Flower-Loving Fly is only known to occur in Riverside and San Bernardino Counties and is endemic to the Colton Dunes Ecosystem. They are only known from a few locations due to their habitat specificity. They are scarce due to habitat loss and degradation.

The characteristic feature of this species’ occupied habitat is fine wind-blown sandy soils, often wholly or partly within sand dunes stabilized by sparse native vegetation. Their diet is nectar from buckwheat and other plants.

Delhi Sands flower-loving fly undergoes a complete metamorphosis from egg to larva to pupa to adult. Oviposition (egg-laying) occurs within loose, sandy soils in the late summer. Eggs are placed 1 to 2 inches beneath the surface of the sand. Larval stages develop completely underground and emerge as adults from July through September.

Life Stage/Activity PeriodJanFebMarAprMayJunJulAugSepOctNovDec
Adult Flight Season (breeding)
Threats and Management Actions

The primary threat to the Delhi Sands flower-loving fly is loss of habitat, habitat degradation, and habitat fragmentation. Management is primarily habitat protection and enhancement.

How you can help: Try to avoid using pesticides and herbicides at your home. Residuals from these products enter natural areas and are detrimental to species such as the Delhi Sands Flower-loving Fly.

This website is being developed by ICF in coordination with the Upper Santa Ana River Sustainable Resource Alliance and Stillwater Sciences.