216. Smith's Blue Butterfly

Smith's blue butterfly on buckwheat. Photo by Tom Moss.
Photo of seacliff buckwheat (Eriogonum parvifolium) 
under a measuring tape for vegetation monitoring.

216. Smith’s Blue Butterfly: Depending on Buckwheat to Survive (1 minute and 27 seconds)
Michelle dela Cruz, Student Volunteer 

Hello! My name is Michelle dela Cruz and I am a student volunteer at California State Parks. If you happen to spot a butterfly that has blue wings and is about the size of a quarter, you’d be lucky—it might have been a Smith’s blue butterfly!

These butterflies are uniquely adapted to the coastal dunes of central California. They have been federally endangered since 1976 due to habitat loss and coastal development.

Smith’s blue butterflies will only eat, mate, and lay eggs on coast and seacliff buckwheat—they cannot survive without these plants. Buckwheat needs open space to grow, but they are crowded out by ice plant and other non-native plants.

The butterfly larvae eat buckwheat flowers and produce sugary food for nearby ants. In return, the ants protect the larvae from predatory insects. After a few weeks, they form cocoons and spend nearly 1 year developing into butterflies.

Seen from above, males have blue wings, while females are brown with an orange bar at the bottom of their lower wings. They emerge between June and September and have 1 week to find a mate before they die; but they only fly during the day when the weather is warm and not too windy.

California State Parks is working to restore the dunes with buckwheat corridors to support the Smith’s blue butterfly population.