Deformed wing virus (DWV) is an RNA virus of the Iflavirus genus that causes wing deformations in adult honey bees. All developmental stages can be infected. If the larvae are already infected, crippled wings, distended abdomen and discolouration occur during metamorphosis, so that the animal dies directly after hatching. The virus causes a latent infection that persists. Thus, even bees without symptoms can be carriers. The mite Varroa destructor is, among other things, a carrier of this virus and its spread to other colonies is a major problem in the spread of this disease. There is no causal therapy.