Dectes stem borer: Biology and ecology

The Dectes stem borer overwinters as a larva in the base of hollow, girdled stems. Larvae will move to the stems of new growth in the spring, feed and eventually pupate in the stems from May to July for 10-15 days. Adults of this univoltine insect will begin emerge throughout late June to September and shortly after emergence deposit eggs in soybean petioles. Larvae quickly migrate from the petioles to the main stem to feed and eventually girdle the stem at soybean maturity at about 1-2 in (3-6 cm) above the soil line. The Dectes stem borer has wild hosts in a number of native hosts such as cocklebur (Xanthium strumarium), giant ragweed (Ambrosia artemisifolia and A. trifida), and wild sunflower (Helianthus annuus) (Michaud and Grant 2005<).