Willow (Salix)-Western tiger swallowtail

Western tiger swallowtail (Papilio rutulus)

Pest description and damage The tiger swallowtail larvae feed on leaves of cherry family plants, willows and a few other species. Generally limited to isolated numbers on single trees. Larvae spin a silken pad on which they rest. Initially larvae look like small bird droppings molting into bigger black and white bird droppings. The last molt is a thick green larva with black and yellow bands and conspicuous eyespots behind the head which is tucked under the body of the caterpillar. When disturbed the larvae may evert orange "horns" with a peculiar smell to deter predators. The chrysalis is a 1 inch long tan, marbled capsule with visible outlines of legs, antennae, eyes and proboscis. The benefit of the large yellow and black butterfly in the garden outweighs the minimal damage inflicted by a caterpillar.

For biology and life history, pest monitoring and management options

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