The species of Pulvinaria are similar in their appearance and damage symptoms. All of them have a wide host range and they are usually a problem in trees, shrubs and other woody plants.
Life cycle and appearance of Wax scales
In the open field, the Pulvinaria species are most easily seen during early summer when females produce their conspicuous ovisacs.
Mature P. hydrangeae females are mainly found on the underside of leaves. They are ovoid to circular, yellow or brown and 3-5 mm long. The eggs are laid in a mass of waxy fibres (the ovisac) which is approximately 10 mm long. The adult females usually die and drop off the ovisac after oviposition, but the ovisacs can persist on the plant long after the eggs have hatched.
The woolly vine scale oviposits on bark, usually on smaller branches. The horse chestnut scale also oviposits on bark, but usually on the trunk and major branches of its host plant.
The cottony camellia scale oviposits on the underside of leaves. It produces longer ovisacs than the hydrangea scale.
The nymphs of these scales hatch in summer and the crawlers wander around on the plant before they settle down and start to feed and develop. They overwinter in the second or third nymphal instar and complete their development in spring.
Heavy infestation can cause host plants to suffer loss of vigour and leaves may fall off. Honeydew and the sooty mould growing on it can contaminate leaves and fruit and reduce photosynthesis as well as attract large numbers of ants.