Bionomics of Stibadium spumosum (Lepidoptera: Noctuidae), a Pest of Sunflower in the Southern Plains

Larvae of Stibadium spumosum Grote inhabit the inflorescence of common annual sunflower, Helianthus annuus L., in southern latitudes of the United States. A single larva of S. spumosum may consume up to 50% of achenes in an H. annuus receptacle. A minor part of the S. spumosum population appears to be bivoltine in the southern Plains. However, univoltinism is the rule, with an obligatory pupal diapause lasting from 6 to 13 months in varying laboratory conditions. At Bushland, Tex., pupal development required an average of 133 days in ambient soil conditions. Parasitization of second instars by six species of Hymenoptera ranged up to 50%. Small larvae also were preyed on by larvae of Phyllobaenus pubescens (LeConte) at Bushland, Tex.