Tiny Black Bugs on a Weeping Willow

Many insect pests infest weeping willow trees.

Weeping willows are very aggressive, fast-growing trees that reach about 45 feet in height and width. They succumb to a wide array of insect pests, making them a poor tree specimen in the home landscape.

Types

Of the many insects found to infest weeping willows, two are tiny black bugs. The smallest of these are aphids, reaching only 1/10 inch in length. They range in color from white or cream to yellow, green and black. Leaf-feeding beetles, some of which are black in either the larvae or adult stages, reach 1/4 inch to 1 inch in length, depending on the type.

Effects

Aphids, found in clusters on the underside of leaves, quickly infest plants, sucking plant juice from the leaves and excreting a sticky substance known as honeydew. They cause foliage wilting and discoloration. Adult beetles feed on leaf tissue, leaving behind the veins. Larvae feed on leaves from below, leaving holes in the leaves. Insect infestations weaken the tree, increasing the risk of other diseases or infestations.

Prevention/Solution

North Dakota State University Extension Service recommends using an insecticidal soap to control insect pests on weeping willows. Both aphids and leaf beetles succumb to acephate, diazinon, carbaryl and malathion.

References

• North Dakota State University Agriculture: Common Insect Pests of Trees and Shrubs in North Dakota
• North Dakota State University Agriculture: Hortiscope
• Missouri Botanical Garden: Trees: Not Recommended
• University of Florida IFAS Extension: Weeping Willow
• North Dakota State University Extension: Questions on Willow
• North Dakota State University Agriculture: Insecticides

Resources

• Ohio State University Extension: Salix--Willow