Hawthorn Leaf Miner: Appearance, Territory, Damage and Life Cycle

Latin Name: Profenusa Canadensis

Appearance: Profenusa canadensis, a hawthorn leafminer, is a somewhat frequent pest issue on hawthorn trees in May and June. The leafminer is a sawfly’s larval stage. The larvae live inside the leaf and brown the tips. The leaves appear to be diseased or injured by frost. However, by exposing the leaves to the sun, frass and, on rare occasions, larvae can be observed between the upper and bottom epidermis.

Hosts Plants: Crataegus Crusgalli is the primary target of the Hawthorn leafminer. Leafminer are drawn to healthy, aggressively developing trees that can withstand harm in general.

Territory: Europe

Damage Insect Cause: Damage looks to be disfiguring in early June, but trees are not destroyed, and by mid-summer, new growth hides the damaged leaves. The destructive stage of this insect is a greenish larva that feeds on tissue between the epidermal layers of a leaf’s epidermal layers. One, two, or even three sawfly leaf miners may be present in a high percentage of leaves in severe Profenusa canadensis infestations, and a large fraction of the foliage present during the early part of the growth season may be destroyed.

Life History and Habits: The winter is spent in the soil by the hawthorn leafminer. Adults emerge just as the leaves start to emerge and deposit their eggs on the leaves. Newly emerging larvae burrow into the inner leaf tissue and feed towards the tip of the leaf. Each leaf may contain numerous larvae. By mid-June, the larvae have grown to approximately 3/8 inch in length. They then pierce a hole in the lower leaf surface and fall to the ground to pupate. Each year, there is just one generation.