LIFE-CYCLE OF CHROMATOMYIA-FUSCULA (ZETT) (DIPT AGROMYZIDAE), A PEST IN NORWEGIAN CEREAL FIELDS

The leafminer Chromatomyia fuscula is reported to have one generation per year. It is the first agromyzid species shown to overwinter as adults. Eggs are deposited inside the leaves of cereals and grasses in late May and in June. The larvae mine the leaves in June and early July, and pupate in the mines. In July and early August the next generation of flies emerge and migrate to unknown overwintering sites. The middle leaves of spring barley support the highest number of larvae, often 10-15 per leaf, while the first two leaves and the flag leaf are less attacked. In the investigated fields, populations of 5.8-64.0 larvae developed per main shoot.