Various species of caterpillars chew on the leaves of local oak trees. These species include: Western tussock moth ( Orygia vetusta), California oakworm (Phryganidia californica ), and Fruittree leafroller (Archips argyrospilus) to name a few. There are other larvae that may chew oak leaves. Certain conventional insecticides or formulations of Bacillus thuringensis may be used to control larvae populations. Conventional insecticides are generally non-specific to their targets, while the Bacillus thuringensis sprays are target specific to moth and butterfly larvae.
Thank you for your great work—as always. Marta, Menlo Park