Drosophila strain W, stock number 5905 was obtained from Bloomington stock center (Indiana University, USA) and used to perform live imaging experiments. Fly larvae having reached the third instar stage whilst feeding on standard food were dissected in hemolymph-like HL3 saline (70 mM NaCl, 5 mM KCl, 1.5 mM CaCl2, 20 mM MgCl2, 10 mM NaHCO3, 5 mM trehalose, 115 mM sucrose, 5 mM sodium HEPES, pH 7.2). For live tissue imaging ER-Tr red and NRB-AF12 were added to the medium of dissected larvae and images acquired using a Nikon eclipse C1 confocal microscope and a Nikon Fluor 60x NA 1.00 water objective.