Aphids (Capitophorus fragariaeTheob.) allowed to feed for several days on a strawberry plant with severe crinkle transmitted two viruses. The isolation and properties of one (virus I) have already been described. The other (virus 3) was separated by transferring the aphids to fresh indicators after 24 hr.Virus 3 was transmitted by aphids which had been allowed to feed on an infected plant for 6 days or more and persisted in the vector for several days. There was some evidence that the virus has a latent period in the vector. The symptoms produced by virus 3 onFragaria vescaand Royal Sovereign strawberry are described.On Royal Sovereign, viruses 1 and 3 together produced symptoms of severe crinkle and viruses z and 3 together produced yellow‐edge. A form of severe crinkle is thus shown to be caused by a virus complex which can be resolved by means of the vector, and severe crinkle is shown to be etiologically distinct from mild crinkl