Oakworm caterpillars are black with eight orange-yellow stripes, are and about 2 inches long when fully grown. The second segment behind the head has two long, curved “horns”. Trees in forests, parks and cities can be defoliated. Red and white oaks are potential hosts for the oakworm, but in Maryland, species in the red oak [...]
If your plant leaves look like someone was doodling squiggly lines, you have leaf miners. Leaf miners are the larvae of various beetles, flies, moths and sawflies. The adult lays their eggs on the leaf and the larvae burrow into the leaf and tunnel through it, feeding and leaving a transparent trail of where they’ve [...]
Leaf infections called leaf spot is caused by a variety of fungi and some bacteria on many trees. An especially harmful version of this disease is called anthracnose which attacks many tree species including dogwood and sycamore. Positive identification usually requires laboratory diagnosis. A leaf spot disease creates spots on foliage. The spots will vary [...]
Leafhoppers are sucking pests related to aphids. They can be quite colorful, but this is lost on their small size (up to about 1/4 inch). As implied by their name, leafhoppers can jump and both nymphs and adults react quickly to disturbances. Leafhoppers are sap feeders on a wide variety of plants. Their feeding damage [...]
Lace bugs are common pests of a variety of ornamental trees and shrubs. The adults have highly ornamented wings and a hood-like structure covering the head. The entire surface is covered with veins that look like lace. Lace bugs are usually detected when their damage to the leaves of host plants becomes evident. The nymphs [...]
The Japanese beetle (Popillia japonica Newman) is a highly destructive plant pest of foreign origin. It was first found in the United States in a nursery in southern New Jersey in 1916. In its native Japan, where the beetle’s natural enemies keep its populations in check, this insect is not a serious plant pest. In [...]
Like the tale of the sorcerer’s apprentice, the gypsy moth is an example of an experiment gone horribly wrong. The moth was brought to the United States in 1869 in a failed attempt to start a silkworm industry. Escaping soon after, the gypsy moth has become, over the past century, a major pest in the [...]
The elm leaf beetle, Pyrrhalta luteola, is a serious pest of ornamental elms and zelkova in Maryland. This insect is native to southern Europe and was introduced to our area during the 1800’s. It will feed on all species of native and introduced elms including American, English, Chinese and Siberian elm. All stages of the [...]
Cytospora canker is a fungal disease that attacks and kills individual branches of primarily mature spruce trees, in particular the Colorado Blue Spruce. One by one the branches begin to discolor from the bottom of the tree upward until the otherwise striking pyramidal form of the tree is compromised. Cytospora fungus naturally occurs as a [...]
Crown rot is a disease which affects many different types of plants. Plants afflicted with this disease experience rot around their stems, in the area where the stem joins the root. Typically, crown rot is fatal, although it can be treated in some cases if a gardener is willing to put in some extensive efforts. [...]