The
appearance of hundreds of caterpillars hanging by silk threads from this
oak tree caused the appearance of tape to prevent unaware pedestrians from
walking under the tree and being covered by the hungry little creatures.
Experts indentified them as California Oak Moth larvae which regularly
infest area oaks between spring and fall each year. Prior to the
tree being roped off, the infestation next to the library caused concern
as unsuspecting people walking under the tree became "caterpillar taxis"
when they walked into the Davidson Library.
According to the experts, the larvae will eat leaves on the tree as well as ones that have fallen on the ground. Healthy oaks will usually grow new leaves after a single defoliation although the tree will be weakened since it takes a lot of energy to do this. Trees will usually survive up to three defoliations by the larvae, and as someone noted, the California natives have survived for centuries without human intervention.
UC's Integrated Hardwood Range Management Program says of the pests:
Statewide, there were many infestations of these pests this year. Both
pass through 4 forms: egg, larvae, pupae, and adult. The larvae, or caterpillar,
is responsible for the damage to oak trees. The young oakworm caterpillar
is hairless and yellowish-green with dark stripes and has a head that appears
too big for its body. Mature caterpillars are mostly black with prominent
stripes. With warming temperatures and the new flush of leaves in spring,
the tiny caterpillars begin feeding in earnest on the new foliage. You
may see hundreds eating leaves, hanging on fine silk threads from oak trees,
moving on the ground, even on your house! After about 6 weeks, the caterpillars
become adults, a brown moth. The adults do not eat but live only
to mate and lay eggs. This whole process, egg to adult, occurs two or three
times per year. Depending on the duration of warm weather, oakworms can
be active from early spring to late fall. Even into the fall, the U.C.
Cooperative Extension Office in San Luis Obispo is still receiving inquiries
about this pest.
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Several people were concerned about the worms' potential for library
contamination and others were simply "creeped out" by the wiggly critters.
But proving once again that the library is a place where differing points
of view are always encouraged, a few people spoke out in the insects' defense.
The Library Receiving folks found them "to be colorful, cute and more than
a little cuddly" and temporarily adopted one or two.
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Whether it was just time to move to their next stage in the cyle, or
whether the rain speeded up the process, the caterpillars disappeared by
the end of the week
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