Weeds, Insects & Diseases

Wheat stem maggot [Meromyza americana], Diptera


Insect Biology

Overwinters as a larvae hidden inside the lower parts of the stem of wheat or other hosts. Larvae form a pupa the following spring and adults emerge in June. Eggs are laid on the leaf blades or stems on which the hatched larvae feed. The young mag...


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Description

Young larvae/maggots hatch from the eggs and burrow into the stem. The larvae are not colorful, pale green or cream in color, legless, and are about 0.25 inch long at maturity. After feeding, the larvae pupate within a cigar-shaped, pale green pup...


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Management

Whiteheads are conspicuous in green fields but rarely affect more than 1-2 percent of the crop.


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Insect Biology

Overwinters as a larvae hidden inside the lower parts of the stem of wheat or other hosts. Larvae form a pupa the following spring and adults emerge in June. Eggs are laid on the leaf blades or stems on which the hatched larvae feed. The young maggots crawl down inside the leaf sheaths and tunnel inside the plant. When mature, larve pupate inside the stems. Second generation adults emerge in mid-summer and lay their eggs on wild grasses or immature volunteer grain. Larvae produced by this generation overwinter. The head of an infested plant dies and turns white while the lower stem and leaves remain green. The condition is referred to as "whiteheads" or "silvertop". In wheat, feeding occurs above the upper node.

Larvae Description

Young larvae/maggots hatch from the eggs and burrow into the stem. The larvae are not colorful, pale green or cream in color, legless, and are about 0.25 inch long at maturity. After feeding, the larvae pupate within a cigar-shaped, pale green puparia.

  • Wheat Stem Maggot
  • Wheat Stem Maggot

Pupae Description

Slender in shape, pale green in colour.

Adult Description

The adults are colorful yellowish-white flies, about 1/5 inch long, with three conspicuous black stripes on the thorax and abdomen, and bright green eyes. Eggs are deposited singly on leaves or stems.

Management

Whiteheads are conspicuous in green fields but rarely affect more than 1-2 percent of the crop.