Which insect causes 1-2 percent field-wide white heads due to larval feeding in the stem?

• A. Army Cutworms
• B. Wheat Head Armyworms
• C. Wheat Stem Maggots
• D. False Wireworms

Answer: (C)

When larval feeding is happening inside the stem, grain development is interrupted, so the heads don’t fill properly and stay pale or white. That specific symptom pattern—field-wide white heads from larvae feeding inside the stem—is best explained by wheat stem maggots. The maggot stage develops inside the stem, tunneling and consuming internal tissues, which blocks nutrients to the developing head and leaves a white, underfilled head at harvest.

You can confirm by inspecting stems at the base or near the head: cut a stem lengthwise to look for internal tunnels or evidence of a larva inside and for frass. The adults are small flies, but the telltale sign in the field is those white, underdeveloped heads caused by feeding from within the stem.

Other insects listed don’t produce this exact pattern. Army cutworms mainly chew foliage or seedlings and don’t cause white, stem-internal head filling. Wheat head armyworms target the heads themselves but feed in the spikelets rather than inside the stem tissues. False wireworms affect roots or soil-connected tissues rather than the stem interior of the head.