Q. What is that caterpillar on my oak tree? — Pam D. Atascadero
A.The California oakworm is probably your pest. The life cycle of an oak moth starts with an egg, which hatches and develops into a larva (caterpillar), eventually transforms into a chrysalis (pupa), and then fully matures into an adult California oakworm moth.
The oakworm is a small light green caterpillar with a dark brown head and dark stripes on its sides. The oakworm moth may be spotted during the summer months.
The California oakworm’s favorite food of choice is a California native, the coast live oak. Don’t panic! Healthy oaks will tolerate oakworm feeding and even defoliation without serious harm. Therefore, treatment to control oakworms is usually not recommended.
Control oakworms and protect oaks with an integrated pest management (IPM) program that relies primarily on the conservation of natural enemies and good cultural practices. Yellow jackets, garden spiders and birds are good predators of oakworms. Providing a birdbath may help increase the presence of birds in your yard.
For more information and photos of the California oakworm moth and larva, visit the UC IPM website at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7422.html .
Be sure that your tree is healthy and can withstand an oakworm outbreak by considering the cultural care of your tree.
Mature oaks do not need irrigation, unless supplemental irrigation is needed during a time of winter drought. Oak trees can be adversely affected by well-watered lawns, compacted soil, or damaged roots caused by construction or nearby pavement. The UC Division of Agriculture and Natural Resources offers a free download of its publication “Living Among the Oaks,” a guide to keeping your oak trees healthy so they can thrive for generations to come.
Save the date! The UCCE Master Gardeners eighth annual Tomato Extravaganza will be from 10 a.m. to 2 p.m. on Sept. 6. There will be tomato and basil tasting, guest speakers and lots of fun! See you there!