Photo Library: Insects
The sunflower headclipping weevil, Haplorhynchites aeneus (Boheman)
Damage is usually insignificant, although losses of up to 10% have been noted in North Dakota. Differences in damage due to planting date were evident in certain locations in Kansas.
The female chews around the stem just below the bud. Often the head is
completely cut off, but sometimes not. Heads will sometimes be able to
complete development with a scar on the stem from the feeding site. The
female lays eggs in the cut head and the larvae develop in the decaying
head. Often the female weevil will hide in the ground near the cut head
on the ground. There are no control measures for this insect since
damage in fields has not been economic. Often it will clip a number of
heads on the margin of a cultivated field.