Abstract: A wind turbine blade includes an upper shell with a first portion molded to a second portion by a seamless connection extending along at least a majority of the width of the upper shell. The wind turbine blade also includes a lower shell with a third portion molded to a fourth portion by a seamless connection extending along at least a majority of the width of the lower shell. The first, second, third and fourth portions are made of a fiber reinforced resin construction. A first insert is enveloped within the upper shell between the first portion and the second portion, the enveloped first insert defining a first spar portion. A second insert is enveloped within the lower shell between the third portion and the fourth portion, the enveloped second insert defining a second spar portion. The inserts defining a density lower than the density of the fiber reinforced resin material. The upper shell is bonded to the lower shell adjacent the right and left sides thereof.