Pest Profile

The sunflower stem weevil is a pale, speckled weevil 4-5 mm (3/16 inches) long with a short, curved snout that is held downwards beneath the head. The eyes, snout and antennae are black. Adults are cryptic and very reclusive, responding to disturbance by scurrying around the opposite side of a stalk or falling from the plant. They may spend many hours of inactivity concealed in small aggregations within dried up cotelydeons while plants are still young. Plants between the V8 and V12 stage seem to be preferred for oviposition, and oviposition punctures in the main stem gradually become evident as they scarify and form blackened callous tissue. Initially, most ovipositions occur around the lower leaf nodes, but later they can occur higher up on the stalk if there is competition for oviposition sites. Larvae are cream colored and can be easily found within their galleries by splitting stalks lengthwise to their base with a stout-bladed knife.