Summary.1An account is given of some preliminary experiments with insects as transmitters of potato mosaic disease. The various types of insect‐proof cage which have been used in these experiments are described.2The following insects were used in the inoculations:Aphididae.Myzus persicae.Macrosiphum gei(=solanifolii).Myzus Circumflexus.Aleurodes, White‐fly.Asterochition vaporariorum.Capsidae.Calocoris bipunctatus.Lygus pabulinus.Typhlocybidae, Leaf‐hoppers.Zygina pallidifrons.Eupteryx auratus.3The aim of the experiments is definitely to identify what insects of those normally attacking the potato are disseminators of virus disease.4Infected insects were placed both upon the sprouts of tubers and upon the haulm; the latter is the only satisfactory method for insects other than aphides.5Successful transmission of mosaic disease was obtained in 1925 by means of the aphidesMyzus persicaeandMacrosiphum gei. Some evidence of infection by means ofAslerochiton vaporariorum(greenhouse white‐fly) and the leaf‐hoppersZygina pallidifronsandEupteryx auratuswars also obtained; further work with these insects is required before definite conclusions are drawn. The capsid bugsLygus pabulinusandCalocoris bipunctatwfailed entirely to transmit th