Yeah California has enough eucalyptus. I second the suggestion to plant native local plants that get the goals you want (eucalyptuses are the opposite of native).

In Santa Cruz, California, where monarch butterflies roost in winter:

"The number of Natural Bridges’ overwintering butterflies is still down more than 95 percent since 1997, and the Tasmanian blue gum eucalyptus canopy that has sheltered generations of butterflies is falling apart."

"Eucalyptus trees have small leaves that are thin enough for monarchs to wrap their feet around. For longer than anyone can remember, those trees have also provided the butterflies a convenient food source and a haven during the winter months, like a warm blanket or an umbrella to protect them from the wind and rain."

https://www.goodtimes.sc/eucalyptus-grove-monarch-butterflie...