Sunflowers are garden favorites for their festive flowers and tasty seeds---that is, until some common insect pests hijack them.
If a sunflower head looks distorted or ‘dirty’ with webbing and gritty beads on it, it could be infested with larvae of the sunflower moth, Homoeosoma electellum. The larvae consume the developing seedsas well as contaminate the entire head with their silk and frass (poop); this, in turn creates a great environment for fungus growth.
|Sunflower moth larvae, Homoeosoma electellum.|
(Photo: C. Sutherland NMSU)
Sunflower Stem Borer
The hatchling ‘sunflower stem borer,’ Dectes sp., bores into the pith of its host, weakening the plant and/or the flower stem. Parts of affected plants may wilt permanently, or entire plants may flop over in the wind. This particular larva is the immature stage of a ‘long horned beetle’---NOT a caterpillar.
|Sunflower stem borer larvae Dectes sp.|
(Photo C. Sutherland NMSU)