Description of the Pest
The wheat stem maggot larva is as drab as the adult is colorful. Mature larvae are about 0.25 inch in length and are pale green or cream colored; they are a typical legless maggot and are generally found inside the stem. The adult is a small, yellowish white fly with bright green eyes and three black stripes across the thorax and abdomen.
Damage
Injury caused by the wheat stem maggot is obvious but usually not serious. Eggs are laid in September and October and hatch later in fall. The young maggots overwinter. When development resumes in spring, damage is caused by maggots feeding in the upper portion of the stem, which cuts off nutrient flow and the heads turn a whitish color. These white heads may be distinguished from those caused by wireworms or root rot by pulling on them. Stems damaged by stem maggots easily pull free where it has been chewed and slides out of the leaf sheath. Infested plants also have fewer tillers than healthy ones.
Management
Injury in California is minimal and chemical controls are not recommended.