Red pine needle midge

Larva in a needle sheath of red pine Thérèse Arcand

French common name: Cécidomyie du pin rouge
Scientific name: Thecodiplosis piniresinosae Kearby and Benjamin
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Cecidomyiidae

Distribution

Eastern Canada

Damage, symptoms and biology

Browning of the current year's needles in September is the primary symptom that can be used to confirm the presence of the red pine needle midge. Premature shedding of the needles can be observed later in the fall and during the winter.

Early scouting can help to detect the insect, especially during heavy infestations. Affected needles are much shorter than normal ones, and the tissues of the needle sheath will have become necrotic and hardened, owing to the hollowed out needle base.

Adults emerge between late May and early June and lay their eggs on the developing shoots which are still covered by bud scales. Single eggs or egg clusters can be found at the base of new needles bundles. The young larvae bore into the needle sheath before it matures and feed between the two needles or on their surface between sheath and needles.

In October, larvae fall to the ground and overwinter in the larval stage in the litter.

Other information

The red pine needle midge has been recorded in North America since 1932, particularly in red pine plantations.

It only causes major damage occasionally and on a very localized scale. However, during heavy infestations, lateral and terminal shoots may die if they lose more than 75% of their needles. Although this insect does not threaten the survival of trees, tree growth will be reduced if large insect populations persist for two or three years.

A shady, cold site will delay adult emergence and vigorous trees with rapidly elongating annual shoots hinder egg-laying.