Willow beaked-gall midge, Mayetiola rigidae (Osten Sacken), (Diptera: Cecidomyiidae): differential susceptibility of willows [Salix]

Beaked galls of Mayetiola rigidae (Osten Sacken) occurred on 51 accessions of Salix species, hybrids, and cultivars out of 125 accessions examined at the Beltsville Agricultural Research Center. In some cases, young galls died while the larvae in them were still small, indicating hypersensitivity to midge attack. Larval mortality also occurred in fully grown galls. In these, the tissue lining the larval chamber either darkened and died, or proliferated into the chamber. Larvae in these galls typically developed to the 3rd instar before dying. Susceptibility to midge infestation was most pronounced in accessions of S. caprea L., S. cinerea L., S. muscina Dode, their hybrids, and a few other species, and least in accessions of S. alba, S. eriocephala Michx., S. purpurea L., their hybrids, and a few other species; 74 accessions were not galled.