Western Tussock Moth Caterpillar

Unidentified caterpillar
Location: Los Altos, CA (South San Francisco bay area)
May 1, 2011 10:53 pm
We saw this guy today (May 1, 2011) at a park in Los Altos California. The pic was taken about 7:30pm and it was about 75 degrees F. It was crawling on an artificial rock play climbing structure on the playground. Can you help us identify it?
Signature: Rolf F

Western Tussock Moth Caterpillar

Hi Rolf,
Your Western Tussock Moth Caterpillar,
Orgyia vetusta, shares many similar characteristics with its close relatives in the genus.  BugGuide only reports this species from California, though its relatives including the White Marked Tussock Moth, Orgyia leucostigma, are found throughout North America.  You should handle the Western Tussock Moth Caterpillar and its relatives with caution because BugGuide notes:  “Contact with hairs may cause an allergic reaction.

8 thoughts on “Western Tussock Moth Caterpillar”

  1. Be sure to keep your distance. Blood from this species will burn you. They will leave blisters and boils on the skin as a defense mechanism designed to repel birds.

  2. Found one of these on my Rosey Buckwheat yesterday. I was going to leave it alone until I read more about what it actually was and how destructive these caterpillars can be.

  3. I have thousands in our yard this year. It is really unbelievable. I have never used sprays or chemicals before, but I had to purchase some BT and sprayed the shrubs last Sunday. I am going to spray again this Wednesday. I am also hiring someone to cut some of the ceanothus shrubs down and haul them away. It is very worrisome. Last March there a few but this year is something out of a nightmare.


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