The weeping willow (Salix babylonica) is a deciduous tree notable for its graceful, cascading leaves and ability to thrive in wet, water logged soils. Reaching an average height of about 50 feet, the weeping willow is a popular tree for temperate regions across the globe. Like all trees, the weeping willow is susceptible to number of different bug species, many of which can be treated before serious damage is done to the tree.
Willow trees are susceptible to a wide range of bugs, including but not limited to carpenterworms, gall mites and leaf beetles. Carpenterworms are boring caterpillars that may be as long as three inches, with greenish white bodies and dark brown heads. Gall mites are tiny yellow or orange insects that collect in groups on the underside of leaves. Leaf beetles are oval shaped beetles that reach an average size of about 1/3 an inch. They can be found feeding on foliage.
The carpenterworm feeds extensively on the bark of the willow tree's trunk and branches, which may cause breakage during storms or high wind. The weakening of the tree caused by carpenterworms may be especially dangerous if the willow tree is in an urban area. Gall mites cause an raised blistering on willow leaves, and though unsightly, the bugs aren't especially harmful to the tree. Leaf beetles cause unattractive notching on plant leaves, which may cause premature dropping.
Carpenterworms, which hide deep within the tree, are difficult to identify, and may require the services of a professional. Often, predatory nematodes are used to control carpenterworms. Gall mites are difficult to remove. The best solution for the insects is simply to prune away infected areas to reduce the population. Leaf beetles are better off prevented than treated, but infested trees can be pruned to lower the population. The larvae of the leaf beetle may get into the soil, where they can attack tree roots. Predatory nematodes may be used to control the larvae population.
A healthy weeping willow tree is much less likely to be attacked by bugs than a willow tree that is in poor condition. If you plant the weeping willow in the right conditions and tend to it regularly, the tree will be better able to protect itself against pests. Weeping willows do best in bright sunlight in USDA zones 4 to 9. Plant the tree where it can get plenty of water, ideally by a stream, pond or river.
When pruning or removing infested leaves or branches, take care to sterilize your equipment to avoid spreading the infestation to other plants or trees. You can do this by soaking pruning shears or hand saws in a diluted mixture of bleach and water for about five minutes. You may consider using insecticides to treat some willow pests, however it is wise to try natural methods first. Insecticides are hard on the environment and can be dangerous if kept in the home where a child or pet may accidentally ingest them.