Mayetiola destructor
- Symptoms: Severe infestations of Hessian flies result in stunting of the plants, thin stands, lodging, and reduced yield. Injury is caused entirely by the larvae, which suck juices from plant tissues (see picture). If infestation occurs during jointing, infested stems often will break prior to maturity. The Hessian fly is 3-4 mm long, has a black head and thorax, and a pinkish or yellow-brown abdomen.
- Life Cycle: Adult flies emerge in the spring from pupae that have overwintered in straw or stubble. The minute, oblong eggs are reddish in color and are laid in rows on the upper sides of leaves. The eggs hatch within one week; the white, legless larvae settle behind the leaf sheaths and suck the sap of the plant. They develop into translucent, pale green, slug-like maggots. The reddish brown pupae, commonly called "flag seed" because of their resemblance to the seed of the flax plant, are oval shaped, flattened, taper to a point, and are 3-5 mm long. They are found behind leaf sheaths, usually at a node.
- Hosts/Distribution: The Hessian fly is mainly a pest of wheat, but it may attack barley, rye, and other grasses. This pest has been reported in most wheat-growing areas of the world.
- Importance: This is one of the most destructive insect pests on cereals. Widespread outbreaks have occurred and, in some locations (such as North Africa and the USA), the pest recurs annually.
