Willow Pinecone Gall Midge - Rabdophaga strobiloides
Alpha, Fayette County, Iowa, USA April 28, 2009 Size: ~2.5 cm
Gall on terminal bud of sandbar willow (Salix exigua = S. interior) at edge of wetland. This may be a "pine cone gall", possibly Rhabdophaga persimilis if I am interpreting Felt's book correctly. I cut open a gall (see upper left part of photo) but found nothing inside.