In the garden: Cotoneaster, pyracantha and ornamental species of Malus
On Crops: Apple trees
Throughout UK and Europe (temperate regions only)
Woolly aphids are easily recognized by the mass of white woolly wax that they produce. They are brown or greyish-purple in colour, although this is usually masked by the wax. The woolly mass will often be seen on the spurs or branches that have been pruned as well as within cracks in the bark.
Woolly aphid infestations cause galls to form. These can split to allow cankers and other diseases to develop within the tree.
Check plants often for early outbreaks. Either squash the aphids or try and remove the developing colony with a stiff paint brush. Encourage beneficial insects including ladybirds, hoverflies, and lacewings, which are important aphid predators. Earwigs are also known to predate on woolly apple aphids.
In small outbreaks, a high-pressure spray from the garden hose can help remove aphids from trees. Where aphid problems persist, as a last resort organic pyrethrum-based pesticides are available from garden centres. These need to be applied following the instructions on the label.
Ladybirds and their larvae are very effective predators of aphids and should be welcomed into your garden. Other predators such as hoverfly larvae and lacewings also provide effective natural ways of controlling aphids. Parasitic wasps will also help to control aphid infestations by injecting aphids with their eggs. The eggs hatch into maggots that eat the aphids from the inside out. Eventually the wasp maggots kill the aphids, turning them into 'mummies' before emerging from the mummified bodies as adult wasps. Ants will often farm aphids and collect the sugary honeydew that aphids produce. The ants protect aphids from predators and can move them to new plants to establish new aphid colonies.