This is a late instar larva of a Silverspotted Tiger Moth, Lophocampa argentata. The caterpillars feed on conifers, including amabilis fir, Douglas fir, grand fir, shore pine, Sitka spruce, western hemlock, western red cedar -- a who’s who of what is native here.
This is the time of year they are found walking on sidewalks. Here is their life cycle:
Late summer: Clusters of eggs deposited on needles and twigs. Within few weeks, larvae hatch, start eating and growing, staying together in small tent, go through 1st and 2nd instars.
Fall and winter: Overwinter in tent as 3rd or 4th instars. Periodically active, eating, still tented.
Spring: move away from home, live independently, eat, eat, eat.
May and June (yesterday): Drop from tree, wander on ground, look for secluded spot to spin cocoon. Be discovered on sidewalk by young child walking with parent. Child exclaims, “Oh look, a callipitter!” a mispronunciation so adorable parent knows his/her heart will break a little when she finally gets it right. Caterpillar placed in jar with leaves, often including universal non-food iceberg lettuce, taken to nature centre. Person at desk thinks, Oh, it’s that time of year again. Nature person identifies caterpillar, googles name to show picture of moth and explain life cycle. (Moth book in nature centre library very dusty, same as other books.) Nature person has dilemma: Ask child to put caterpillar back where she found it, which seems ungrateful and uncaring, or gladly accept caterpillar with intent of releasing it, but which bolsters idea that any bug, bird, baby squirrel, etc. found in city should be brought to nature centre instead of being left alone. Caterpillar is released, finds secluded spot, spins cocoon, pupates.
Mid-summer: Moths emerge from cocoons.
Late summer: Clusters of eggs deposited on needles and twigs.