Have you spotted this pest on your apple trees?

Why are woolly apple aphids harmful to their host trees?

Woolly Apple aphids are a common species in Britain, and so many people will have found them in their gardens where the aphids host plants are grown. They first become active during spring, after spending the winter in a dormant state within nooks and crannies on their host tree. Once the season’s temperatures start to increase, the aphids begin feeding on the tree’s sap after pushing their stylets into the bark.

As they feed, they’ll give birth to live young and soon generate a colony on the bark and new shoots. The colony will develop under copious amounts of fluffy light grey wax that the adult aphids secrete from their bodies. This wax shield not only helps to protect the colony from the elements but also from predators.

However, the wax, which can often be mistaken for patches of grey mould on the trees, provides a visual indication of where the aphid colonies are located, which is very useful if the aphids require controlling in commercially grown orchards or perhaps on a cherished apple tree in the garden. The reason why Woolly Apple aphids might need controlling is that besides the messy appearance on the bark, and the sticky honeydew the aphids produce, an established infestation can often cause serious harm to the host tree.

 The reason for this is that when the aphids feed, a chemical in their saliva causes lumpy growths to develop on the tree.  Growths where the tissue becomes much softer than the surrounding bark, making it easier for the aphids to access the tree’s sap. However, the growths will often split as they become larger, allowing fungal canker disease to establish on the tree.

How to control the woolly apple aphids

Controlling woolly aphids is relatively simple if the infestations are accessible and it doesn’t have to involve using chemical insecticides that could harm the beneficial insects that are on the trees, particularly the pollinators. It will just require using a treatment that removes the wax layer that the colony produces and exposing the aphids to the elements and their predators.

This is easily achieved by thoroughly spraying the infested areas with a proprietary soap-based product, such as SB Plant Invigorator, which has been tested and approved for its environmental and plant safety. Repeat the applications as and when required.