Found eating Cistus ladanifer in San Diego County, California, April 6th. Small/young, only 1.5 cm long.
It would be good to take a dorsal and side view of caterpillars for best identification. The dorsal view of this caterpillar indicates it is a rusty tussock moth larva.
I’m guessing if we saw a different view you would see the tell-tale black long tufts of hair coming out the back end and two tufts out the front end that would look a bit like antenna. The white spots are thick tufts on it’s back.
This caterpillar feeds on the foliage of many plants and trees esp in the Rosaceae (roses and most fruit trees), Ericaceae(blueberries, azaleas,heaths, heathers), and Salicaceae (willows, poplars, aspen) families. It is found through out North America though it is native to Europe.
The female moth does not have wings. In fact as she emerges from her pupa cocoon, she mates then lays eggs on the cocoon. These eggs overwinter and emerge in the spring when temperatures warm up. The male has red-brown wings with a distinct white spot on each front wing. The underwings are reddish-orange colored.
Note: Some tussock caterpillars are known to cause a rash if handled, so do not touch this group of caterpillars.