Contents: By Damage and Image
Cottony camellia scale
First described in 1870 by Westwood, the cottony camellia scale, Pulvinaria floccifera (Westwood), shows up most commonly on holly in PNW nurseries and landscapes. It does have a wider host range (at least 35 plant families according to Scalenet) including its namesake camellias, English ivy, euonymous, hydrangea, maple, mulberry, pittosporum, rhododendron and the host by which it is also known, cottony yew scale.
According to the University of Maryland Pest Predictive Calendar, cottony camellia scale eggs hatch at 856 degree days (base 50 degree F) or around the time of full bloom of smokebush, Cotinus coggygria. In the PNW Nursery IPM alert database, we received alerts about cottony camellia egg hatch (eclosion) occurring on 4/29/2016, 7/3/2011 and 6/23/2009 in the north Willamette Valley. This is a key time to control the crawler stage, which is very vulnerable to a range of "softer" pesticides include insecticidal soaps, horticultural oils, and insect growth regulators. Only one generation per year of this scale species has been noted in the Pacific Northwest.
It has been reported that a 2% rate of oil (versus 1% rate) applied during the dormant stage works well.
Bee Aware: Use caution with systemic and contact insecticides to avoid potential insecticide residual during flowering. For more information on bee safety, check out the Pacific Northwest Extension Publication - PNW 591, How to Reduce Bee Poisoning from Pesticides (free downloadable pdf).
Systemic insecticides: Fall timing of imidacloprid gives time for that systemic insecticide to move through the plant to the target tissue by spring. Dinotefuran (Safari) moves more quickly in plant tissue and can be used in the spring. Orthene is reported to have efficacy on this scale as well when used during the dormant stage.
Doubrava, N. et al. 2015. Camellia Diseases and Insect Pests. Clemson Cooperative Extension. <27 April 2016>
Miller, D. et al. 2014. Pulvinaria floccifera. Scale Insects: Identification Tools for Scales of Quarantine Importance. Systematic Entomology Lab. USDA. <27 April 2016).
Raupp, M. 2010. Flocked Hollies: Cottony Camellia Scale, Pulvinaria floccifera. Bug of the Week. University of Maryland.
LivingWithBugs.com: Cottony camellia scale
Cottony camellia scale. PNW Insect Management Handbook.
Orginal publication: 6-22-2009
Author: R.L. Rosetta, Extension Nursery Integrated Pest Management, Department of Horticulture, Oregon State University