July and August
Palm Flower Caterpillars (Palm Budworms) are feeding on the blossoms of some fan palms. Infestations of these cream-colored larva, which may exceed an inch in length, may not be evident until maturing worms drop to the ground and become a nuisance.
The caterpillars usually do little damage feeding on palm flowers and pupating under the peels of the palm. However, they are sometimes knocked out of the trees by high winds or pruning and crawl indoors to pupate. Once inside they chew into carpets , upholstery, or even books to create a pupal chamber.
Link: Palm Caterpillars in the Low Desert: Maricopa County Cooperative Extension Home Horticulture.