By that time, most of the midge should have reached the end of their life. The Spotted stem weevil population has been small in North Dakota for the past several seasons. Jan Knodel, NDSU Plant Protection Specialist in Minot, observed spotted stem weevil last week. There are some concerns about stem weevil in Emmons and surrounding counties. Spotted stem weevil larvae cause stalk breakage when 25 to 30 larvae are present in a stalk, weakening it when larvae make their overwintering cells in the stalk's base.
Breakage is most likely to occur during high winds.
The weevils emerge in mid to late June. Eggs are deposited in epidermal tissue of the stem. If controls are directed at the adults in order to minimize egg laying, treatments should be initiated during the first few days in July. Treatment for sunflower stem weevils is recommended when scouting determines that an average of 1 adult per three plants is found. Moth captures at Oakes and Carrington have been averaging around 15 to 20 moths per night.