Invasion of honeybee brood cells by Varroa jacobsoni in relation to the age of the larvae

Brood combs from highly infested colonies containing larvae of known age were investigated for Varroa. No mites were found in drone cells or worker cells prior to 170 h since oviposition. Combs were invaded during 60 h and 30 h from capping, respectively. Brood combs may thus be changed among colonies before the 7th day without tranferring Varroa. The attractivity of larvae was investigated in dual-choice tests. Larvae were most attractive shortly after capping, while the attractivity decreased during the pupal stage.