|Pulvinaria floccifera Family: Coccidae
Common name: cottony camellia scale; cottony taxus scale; cottony yew scale; cushion scale
Host plant: Camellia, Ilex (holly), Pittosporum (cheesewood), Euonymus (spindle tree), Hedera helix (English holly), Taxus (yew), Hydrangea, Rhododendron
Adult size: Females are flat and oval-shaped; one-eighth of an inch in diameter. Males in 2nd instar stage are smaller. Adult winged males are tiny; difficult to see in flight.
Life Cycle: one generations per year
Description: Adult females are oval-shaped and tan in colour with dark brown edges. They lay their eggs, in late spring, in clusters of up to 1000, inside fluffy cotton-like ovisacs which are roughly a quarter of an inch (6.5 mm) long. Yellowish-brown crawlers emerge in June or July, here in the Pacific Northwest. Hatching crawlers either crawl or are carried by the wind to a suitable leaf where they crawl to the underside, inserting their mouthpart into or beside a vein to suck up the sap. Second instar, immature female crawlers over-winter on the leaves, if the plant is an evergreen, or on the twigs if it is deciduous. They emerge in spring when temperatures reach 10 °C (51 °F). It is unclear whether there is a third instar stage but if there is one for this scale species, only the females undergo this stage and it only lasts for 2 – 4 days. The smaller males go through a pupal stage where they develop wings, emerging in late summer to search for females. The males mate with immature females and die in 1 – 2 days. There is one generation per year.
Special Notes: Male and female sexuality cannot be determined until crawlers reach 2nd instar stage. Females can reproduce both sexually and parthenologically.
Remedial Actions: As this is a soft scale insect…one with a soft body…they are treatable with horticultural oil. (The oil coats the soft-bodied insect and smothers it.) Spray the infected shrub in late winter when temperatures are above freezing and there is a rain-free period of 24 – 48 hours. Be sure to coat both the upper and lower sides of the leaves. This will catch the pregnant females before they have a chance to lay their eggs.
If your timing is off, spray the plant in late June or early July to catch the emerging crawlers. However, do not spray at this time if temperatures are forecasted to reach 35 °C (95 °F). Plants may be stressed and the oil may have an adverse effect on the plant.
In our Zone 7a garden: Sometime around 2010 or 2011, we noticed our 45 year old camellia had a few cottony things on the underside of some of the leaves. There was also some sooty mould on a few leaf tops but as the shrub did not appear to be stressed, we did not worry about it.
However, in late fall of 2014 we noticed there was a lot of black sooty mould on most of the camellia shrub. That was when I went searching for answers and had the pest identified as cottony camellia scale, Pulvinaria floccifera. John sprayed the whole shrub with horticultural oil in February 2015, making an effort to get the undersides of the leaves as best he could. And it paid off. I did periodic searches throughout April, May, June, and July of 2015…only finding a very few old cottony ovisacs and no scales. What a relief.
But…doing a check on a few leaves in January 2017 and I have found a few cotton ovisacs and some over-wintering females. The camellia has been put on the list for a dousing of horticultural oil next month.
Posted on January 25, 2017