Elm: Aphids Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-09-29 06:57 Last edit date: Elm woolly aphid Photo by: A.L. Antonelli Biology Aphids are soft-bodied, pear-shaped insects that feed on the leaves. They are yellowish to green in color and approximately 1/16″ long. Aphids often produce honeydew, a sweet, sticky substance which […]
Elm: Bark beetles Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-05-04 09:05 Last edit date: Bark beetle larval galleries Photo by: A.L. Antonelli Biology Elm bark beetles are about 1/8″ long and may be shiny brown or black. Adults, larvae, or pupae overwinters under bark. Adult beetles emerge in the spring (around […]
Elm: Carpenterworm Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-05-04 09:17 Last edit date: Carpenterworm larval mine Photo by: Unknown Biology Carpenterworms are the larvae of a mottled gray and black moth. The caterpillar are white to pinkish red with a dark head and 1″ to 3″ long when mature. They bore […]
Elm: Elm leaf beetle Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-09-29 06:57 Last edit date: Elm leaf beetles Photo by: Unknown Biology Elm leaf beetles feed on the leaves both as larvae and as adults. The larvae appear in late spring (typically May-June) from eggs laid by overwintering adults. The 1/4″ […]
Elm: Elm leafminer Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-05-04 11:30 Last edit date: Elm leafminer damage Photo by: J. O’Brien Biology Elm leafminers feed by removing green tissue from between upper and lower surfaces of the leaves. Symptoms of feeding by the yellowish or green larvae include large brown to […]
Elm: European elm scale Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-09-29 06:57 Last edit date: European elm scales Photo by: A.L. Antonelli Biology The European elm scale is a reddish-brown to purplish scale surrounded by a conspicuous fringe of white, waxy material. They sometimes resemble mealybugs. The mature females are about […]
Elm: Bacterial wetwood (Slime flux) Categories: Elm Elm Diseases Ornamental trees Ornamentals Last review date: 2026-05-04 08:52 Last edit date: Elm bacterial wetwood (slime flux) Photo by: R.S. Byther Biology Wetwood or slime flux is a bacterial infection common in elm and poplar. The infection causes production of large amounts of moisture in the wood […]
Elm: Dutch elm disease Categories: Elm Elm Diseases Ornamental trees Ornamentals Last review date: 2026-05-04 09:39 Last edit date: Dutch elm disease Photo by: C.R. Foss Biology Dutch elm disease is a fungal infection transmitted by elm bark beetles. Bark beetles carry disease spores on their bodies and infect trees when they feed. Leaves above […]
Elm: Nectria canker Categories: Elm Elm Diseases Ornamental trees Ornamentals Last review date: 2026-05-04 12:04 Last edit date: Nectria canker fruiting bodies on branch Photo by: R.S. Byther Biology Nectria canker is a fungal disease often found on twigs and branches that have been weakened by drought, frost damage, insect damage, or other diseases. Cankers […]
Elm: Spiny elm caterpillar Categories: Elm Elm Insects Ornamental trees Ornamentals Last review date: 2026-08-28 02:06 Last edit date: Spiny elm caterpillar Photo by: S.J. Collman Biology The spiny elm caterpillar is the larval stage of the mourningcloak butterfly. The adult is approximately 2 1/2″ across, with purplish brown to black wings bordered by a […]