Elm leafminer

  • Latin name: Kaliofenusa ulmi Sundevall
  • French name: Tenthrède mineuse de l'orme
  • Order: Hymenoptera
  • Family: Tenthredinidae
  • Synonym(s): Fenusa ulmi (Sundevall)
Description

Distribution

Eastern Canada

The elm leafminer is probably an introduced insect brought to North America on imported elms. In recent years it has caused severe leaf browning on Camperdown elms around Sault Ste. Marie. Today this leafminer can be found throughout eastern Canada and the northeastern United States west to the Lake States.

Micro-habitat(s)

Soil, Leaf

Damage, symptoms and biology

They begin to feed between the upper and lower surfaces of the leaf causing brown blotch-like mines. If several larvae mine one leaf, the mines often coalesce leaving the entire leaf hollowed out. These leaves soon wither, die, and fall to the ground. If a leaf has only been partially mined, holes are left in the leaf.

The insect winters as a prepupal larva in a brown paper-like cocoon found in the topsoil. Pupation takes place in the spring. The adults become active in early May and can still be found during the first week of June. The adults are tiny four-winged sawflies that belong to the order of insects known commonly as ichneumonids, chalcids, ants, bees, and wasps.

Females insert the eggs into the leaf tissue near the vein that runs up the middle of the leaf. Sometimes as many as 25 eggs are laid per leaf. The tiny white larvae, with pale brown heads, soon hatch from the eggs. Full-grown larvae are found by late June and are about 6 mm long. They vacate their mines around the middle of July and drop to the ground where they spin cocoons in which to pupate. There is one generation a year.

Other information

Often ornamental trees are persistently attacked year after year by this leafminer. If the tree is small enough and only a small portion of the tree is affected, handpicking and destroying the mined leaves offers an effective means of control.

Canadian Forest Service Publications

Elm leafminer

Diet and feeding behaviour

  • Phyllophagous : Feeds on the leaves of plants.
    • Miner: Feeds inside the blade of a leaf, between the epidermal layers, or beneath the bark of plants, by first excavating a mine into these tissues.
Information on host(s)

In recent years, the elm leafminer has caused severe leaf browning on Camperdown elms around Sault Ste. Marie. It will also attack English, Scotch and American elms.

Main host(s)

Elms, rock elm, siberian elm, slippery elm, white elm

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