Leafcurl Midge (Prodiplosis morrisi)

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- The larvae distort and kill newly developing terminal leaves on trees of all sizes. In nurseries, heavily injured shoot tips may die. Large trees become flat-topped.

Look For: Distorted, puckered, and folded leaves on terminal shoots and branches, often in distinct whorls with normal leaves in between, found throughout the growing season. Tiny white legless maggot-like larvae within the folded leaves.

Injury caused leafcurl midge Photo by James Solomon, USDA Forest Service

Biology- The mosquito-like female midge deposits numerous eggs on developing shoot tips, preferring the terminals. The larvae feed on the surfaces of the expanding leaves, causing the leaves to become distorted. There may be five or more generations in a season. Each generation damages 1 to 2 whorls of leaves; and because there is a short period between generations, normal leaves alternate with damaged leaves. Larvae of the last generation overwinter in the soil beneath the trees.

Monitoring-  Inspect trees throughout the growing season for one or more whorls of distorted and folded leaves. If 50 percent of the trees are attacked in a nursery, treat the infested area.

Control:

• Till soil in nursery in spring to reduce emerging adults.
• Apply a systemic insecticide recommended for leaf feeding insects.

For Additional Information:

Morris, Robert C. 1981. A new pest of poplars. Pest Control Rep. 13. Maple, ON: Pest Control Section, Ministry of Natural Resources. 7p.